Silencer, exhaust valve, valve device, air dryer, compressed air supply device for vehicle, and compressed air supply system

ABSTRACT

An air dryer includes a supporting base, a drying agent container, and an outer cover. The supporting base includes an inlet for receiving compressed air to be subject to a drying process and an outlet for delivering the processed compressed air that has undergone the drying process. The drying agent container is a container supported on the supporting base, contains a drying agent in the interior, and enables the drying process to be performed by passing the compressed air from the inlet through the drying agent. The outer cover surrounds the outer side of the drying agent container on the supporting base and defines a chamber for storing the compressed air between itself and the drying agent container. The supporting base includes first and second mounting surfaces, which are oriented in different directions, and a plurality of inlets, which are oriented in different directions and receive the compressed air.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 14/666,132filed Mar. 23, 2015, which is a continuation of U.S. application Ser.No. 13/885,387, which is the U.S. national stage of InternationalApplication No. PCT/JP2011/076612, filed Nov. 14, 2011, which claimspriority to Japan Applications No. 2010-255240 filed on Nov. 15, 2010;2010-255286 filed on Nov. 15, 2010; 2010-255288 filed on Nov. 15, 2010;2010-255292 filed on Nov. 15, 2015; 2011-000681 filed on Jan. 5, 2011;2011-027261 filed on Feb. 10, 2011; and 2011-119435 and May 27, 2011.The foregoing patent applications are incorporated herein by reference

FIELD OF THE INVENTION

The present invention relates to an air dryer for performing a dryingprocess on compressed air to be used as a drive source for pneumaticequipment. The present invention also relates to a silencer that reducesair exhaust noise from an exhaust valve in an air dryer performing adrying process on compressed air and to an air dryer that includes thesilencer. The present invention further relates to an exhaust valve thatdischarges drain and air generated from a drying process in an air dryerperforming the drying process on compressed air and to an air dryer thatincludes the exhaust valve. The present invention also relates to aregeneration valve device for an air dryer that has an air feeding timeadjusting function and to an air dryer that includes the regenerationvalve device. The present invention further relates to a compressed airsupply device for a vehicle that supplies compressed air to an air brakedevice, air suspension device, and the like, installed in a vehicle. Inparticular, the present invention relates to a valve device that has anair feeding time adjusting function and to an air dryer that includesthe valve device. The present invention also relates to a compressed airsupply system that supplies compressed air. In the present description,“valve device” refers to a device with a configuration where switchingbetween opening and closing of a valve is performed by moving a piston,arranged inside an enclosed chamber or inside a chamber that is anenclosed chamber, by changing a pressure of a fluid in a space at leastat one side with reference to the piston. Also, “air dryer” refers to adevice that removes moisture, oil, and the like, from a gas containingthe moisture, oil, and the like, to dry the gas.

BACKGROUND OF THE INVENTION

Generally, in a large vehicle, such as a truck or bus, a pneumatic brakedevice using compressed air as a working fluid for actuating brakechambers is adopted. This type of brake device has a configuration wherecompressed air discharged from an air compressor is stored in an airtank and the compressed air in the air tank is supplied as necessary toeach brake chamber. An air dryer for adsorbing moisture from thecompressed air to perform a drying process is located between the aircompressor and the air tank.

Conventionally, as this type of air dryer, a configuration has beenproposed that includes a supporting base including an inlet receivingcompressed air to be subject to the drying process and an outletdelivering processed compressed air that has undergone the dryingprocess, a drying agent container, which is supported on the supportingbase, contains a drying agent in the interior, and enables the dryingprocess to be performed by passing the compressed air from the inletthrough the drying agent, and an outer cover, which surrounds the outerside of the drying agent container on the supporting base and defines achamber storing the compressed air between itself and the drying agentcontainer (see, for example, Patent Document 1).

For example, an air dryer has been known that removes moisture and oilin compressed air delivered from an air compressor in a brake device forlarge automobile. This air dryer includes, in addition to an air intakeinlet for taking in the compressed air (compressed air before removal ofmoisture and oil) from the air compressor and a processed air deliveryoutlet for delivering dried air that has undergone the moisture and oilremoval process, a drain valve for discharging drain, containing theremoved moisture, oil, and the like, together with air (see, forexample, Patent Documents 1 and 3). In the present description, thisdrain valve will be referred to as an “exhaust valve” from thestandpoint of discharging air.

With this exhaust valve, a loud air discharge noise (explosive noise) isgenerated when the valve is opened and therefore to reduce this noise, asilencer, such as described in Patent Document 2, is connected to theexhaust valve in some cases.

Conventionally, as described in Patent Document 4, a drying device (airdryer) has been known that is used in an air brake device of a vehicleto remove moisture in compressed air. The drying device includes adrying container filled with a regenerable drying agent and aregeneration tank storing dry compressed air from which moisture hasbeen adsorbed by the drying agent. The device is configured such thatthe compressed air delivered from an air compressing device is dried bythe drying agent in the drying container and stored in an air tank ofthe air brake device. In this process, some of the dry compressed air isstored in the regeneration tank inside the drying device. It isconfigured that the dry compressed air in the regeneration tank flows inreverse to enable regeneration of the drying agent inside the dryingcontainer.

Also conventionally, in a large vehicle, such as a truck or bus, apneumatic type brake device or suspension device using compressed air asthe working fluid is adopted, and a compressed air supply device for avehicle that supplies compressed air to these respective devices isinstalled. The compressed air supply device for a vehicle includes anair compressor discharging the compressed air, an air dryer removingmoisture and other foreign matter from the compressed air dischargedfrom the air compressor, and an air tank storing the compressed airpassed through the air dryer and supplies the compressed air in the airtank as necessary to the brake device and the suspension device.

As this type of compressed air supply device for a vehicle, a device isknown one that includes a pressure governor located in an unloading pipebetween the air compressor and the air tank. The pressure governorswitches the operation of the air compressor to loading or unloading sothat an air pressure inside the air tank is within a predeterminedrange. When the air compressor is unloaded, opens an exhaust valve ofthe air dryer to regenerate the drying agent inside the air dryer (see,for example, Patent Document 5).

Further conventionally, as described in Patent Document 4, the dryingdevice (air dryer) has been known that is used in an air brake device ofa vehicle to remove moisture in compressed air. The drying deviceincludes the drying container filled with the regenerable drying agentand the regeneration tank storing the dry compressed air from whichmoisture has been adsorbed by the drying agent. The device is configuredsuch that the compressed air delivered from the air compressing deviceis dried by the drying agent in the drying container and stored in theair tank of the air brake device. In this process, some of the drycompressed air is stored in the regeneration tank inside the dryingdevice. It is configured that the dry compressed air in the regenerationtank flows in reverse to enable regeneration of the drying agent insidethe drying container.

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-136403

Patent Document 2: Japanese Laid-Open Patent Publication No. 2007-315209

Patent Document 3: Japanese Laid-Open Patent Publication No. 2009-119426

Patent Document 4: Japanese Patent No. 3167251

Patent Document 5: Japanese Laid-Open Patent Publication No. 2008-213764

SUMMARY OF THE INVENTION Problems that the Invention is to Solve

Generally, this type of air dryer is mounted in a narrow space of avehicle. In many cases, this space differs according to the vehiclemodel in which the air dryer is to be mounted. Therefore, with theconventional air dryer, for each vehicle in which the air dryer is to bemounted, a process of designing positions of a mounting portion and aninlet for compressed air in accordance with a mounting position in thevehicle and forming the mounting portion and the inlet on a supportingbase is performed. The air dryer thus has problems of being poor inversatility and also being poor in productivity.

Accordingly, it is a first object (problem) of the present embodiment toprovide an air dryer that is improved in versatility and productivity byenabling mounting on diverse mounting positions to be performed with thesame configuration.

Also, although as described in Patent Document 2, the conventionalsilencer has a configuration where the air discharged from the exhaustvalve is discharged through a filter member (noise absorbing material)so that a predetermined noise absorbing effect is obtained, thesilencing effect is not necessarily sufficient. Also, the silencer isconfigured to be connected as an independent member to the exhaust valveand there is thus the disadvantage that a large occupied volume isrequired.

Accordingly, it is a second object (problem) of the present invention toprovide a better silencing effect in a silencer provided in an air dryerthat performs a drying process on compressed air and further to providea silencer that does not require the ensuring of a large occupiedvolume.

To clarify a third problem (object) to be resolved by the presentinvention, a configuration of an exhaust valve according to aconventional art will now be described in detail with reference to FIG.30. FIG. 30 is a cross-sectional view of the exhaust valve according tothe conventional art.

In FIG. 30, reference numeral 350 denotes an air dryer that includes theexhaust valve according to the conventional art. The air dryer 350includes, at an upper portion of a base member 352 that is its base, adrying portion 353. Compressed air discharged from a non-illustrated aircompressor is taken into the interior of the air dryer 350 from an airintake port (non-illustrated) formed in the base member 352.

The compressed air taken into the interior of the air dryer 350, fromwhich moisture and oil are removed in the drying portion 353, is outputfrom an output port (non-illustrated) formed in the base member 352,stored in an external air tank, and the like, and used as necessary todrive an air driven device, such as an air brake, and the like. Theconfiguration of the drying portion 353 is not required for explainingthe problem of the present invention and therefore illustration anddescription of the detailed configuration of the interior of the dryingportion 353 will be omitted.

Some of the compressed air from which moisture and oil have been removedin the air dryer 350 is also supplied to a pressure governor(non-illustrated) incorporated in the air dryer 350. The non-illustratedpressure governor outputs a control command pressure for opening theexhaust valve 356, which is located at a lower portion of the air dryer350, when the dry-processed air delivered from the air dryer 350 reachesa predetermined upper limit pressure. In FIG. 30, reference numeral 55denotes a control chamber to which the control command pressure isoutput.

When the exhaust valve 356 is opened, a state is attained where thecompressed air supplied from the air compressor (non-illustrated) isdischarged from the exhaust valve 356, that is, the supply of compressedair into the drying portion 353 is stopped. In this state, the airinside the drying portion 353 flows in a direction reverse to thatduring the drying process due to a pressure reduction action and an oilfilter (non-illustrated) inside the drying portion 353 is therebycleaned and the moisture and oil accumulated in the exhaust valve 356are discharged to the exterior together with the air. Also in thisstate, the dry-processed air inside the drying portion 353 is dischargedto the exterior while taking away moisture from a drying agent(non-illustrated) inside the drying portion 353 and the drying agent isthereby regenerated. Reference numeral 369 denotes a silencer thatreduces an explosive noise that is generated in accompaniment with therapid discharge of air.

When the control command pressure delivered from the non-illustratedpressure governor decreases and the pressure inside the control chamber355 decreases, the exhaust valve 356 closes, and the compressed air issupplied into the drying portion 353, thereby returning to thecompressed air drying process state in the drying portion 353.

With the conventional exhaust valve 356, a vertically moving valve body57 is formed by a piston 358, a valve element (seal) 360, a base 361, abolt 362, and an O-ring 359. In the present description, the assembly ofcomponents that moves vertically in the exhaust valve formed by thepiston 358, valve element (seal) 360, base 361, bolt 362, and O-ring 359(in the case of the conventional art) will be referred to as the “valvebody.”

The piston 358 is formed of a metal material to take on a T-like shapeand is formed by a piston upper portion 358 a of large diameter and apiston lower portion 358 b of small diameter.

The valve element 360 is formed integral to the base 361 by mold formingand is coupled to the piston 358 by the bolt 362 to arrange the valvebody 357. The valve element (seal) 360 is formed of an elastic materialand the base 361 is formed of a metal material.

Reference numeral 363 denotes a valve seat and the exhaust valve 356 isconfigured to open and close by the valve element 360 moving intocontact with and away from the valve seat 363 in accordance with thevertical movement of the valve body 357. The valve seat 363 is formed byan opening formed in a valve base 364, and the valve base 364 is housedin an opening 352 a formed in the base member 352 and is fixed by aC-ring, denoted by reference numeral 367, so as not to fall off in thelower direction. Reference numeral 366 denotes an O-ring that exhibits asealing function.

Also, reference numeral 365 denotes a return spring that urges thepiston 358 in the upper direction (valve closing direction).

Some of the compressed air, supplied from the air compressor in a loadedstate, is supplied to a pressure chamber 354 to generate a predeterminedpressure, and this pressure is applied to both the piston upper portion358 a and the valve element (seal) 360. That is, an upward pressingforce is applied to the piston upper portion 358 a and a downwardpressing force is applied to the valve element 360.

However, when the air compressor is in the loaded state, the exhaustvalve 356 must be maintained in a valve closed state, that is, when theair compressor is in the loaded state, the force pressing the valve body357 in the valve closing direction must be dominant. A pressurereceiving area of the piston upper portion 358 a must thus be formed tobe greater than a pressure receiving area of the valve element (seal)360, and the piston 358 thus has the T-like shape with which thediameter of the upper portion is large as illustrated. The exhaust valve356 is thereby made capable of maintaining the closed valve statewithout fail when the air compressor is in the loaded state.

However, on the other hand, the need to increase the pressure receivingarea of the piston upper portion 358 a makes it necessary to enlarge theopening 352 a (formed in the base member 352) for housing the componentparts of the exhaust valve 356, and the need to reduce the pressurereceiving area of the valve element (seal) 360 makes it necessary toarrange the valve base 364 as a separate member and to form the valveseat 363 thereat.

By the above reasons, with the conventional exhaust valve 356, the valvebase 364 is made large because of the opening 352 a must be made largeand this causes increase of cost. In addition, a predetermined strengthmust be ensured at the C-ring 367 for fixing the valve base 364 becausea high pressure is applied to the valve base 364 when the air compressoris in the loaded state, and this causes further increase of cost.

Also, the piston 358 has the T-like shape with the upper portion oflarge diameter due to the above reasons and therefore, due to reasons ofassembly, the valve body 357, which moves vertically, cannot be made anintegral configuration. In particular, the piston 358 and the base 361cannot be formed integrally and the valve body 57 thus has to be formedby the numerous separate members of the piston 358, valve element 360,base 361, and bolt 362 as described above.

The present invention has been made in view of such circumstances and athird object (problem) thereof is to achieve simplification of structureand low cost in an exhaust valve provided in an air dryer that performsa drying process on compressed air supplied from an air compressor.

Although using the air tank outside the drying device and not providingthe regeneration tank inside the drying device may be considered, thedry compressed air inside air tank will continue to flow in reverse ifthe regeneration tank is simply eliminated.

There is thus a need to make only the necessary amount of dry compressedair for regenerating the drying agent flow in reverse, and a valvedevice that includes an air feeding time adjusting function forrestricting the amount flowing in reverse may be considered.

FIGS. 31(A) and 31(B) are cross-sectional views illustrating problems ofa valve device that includes an air feeding time adjusting function thatthe applicant is considering. Of these, FIG. 31(A) is a diagram showinga manner in which a valve (544, 549) is switched from a closed state toan open state. On the other hand, FIG. 31(B) is a diagram showing amanner in which the valve (544, 549) is switched from the open state tothe closed state.

As shown in FIG. 31(A), the valve device 540 includes a chamber (volumechamber) 543, a piston 541, a valve element 544, a valve seat portion549, and a compression coil spring 545. Of these, the chamber (volumechamber) 543 is configured such that the pressure of air acts on it.Also, the piston 541 is configured to slide in the interior of thechamber (volume chamber) in the axial direction of the piston 541.Specifically, an O-ring 546 is mounted on the outer periphery of thepiston 541 and the O-ring 546 is configured to be in contact with theinner surface of the chamber (volume chamber) 543.

Yet further, the valve element 544 is located at a first end (lower sidein the drawing) of the piston 541 so as to be integrally movable withthe piston 541. By the valve element 544 contacting the valve seatportion 549 located at an opening at the first end of the chamber(volume chamber) 543, the valve (544, 549) is put in the closed state.On the other hand, the valve (544, 549) is configured to be put in theopen state by the valve element 544 separating from the valve seatportion 549. Also, the compression coil spring 545 is located at asecond end (upper side in the drawing) in the movement direction of thepiston 541 in the chamber (volume chamber) 543 and is configured to urgethe piston 541 toward the first end (lower side in the drawing). Thevalve (544, 549) is thus in a closed state in the normal state in whichthe pressure of air is not acting on the interior of the chamber (volumechamber) 543.

Also, for adjusting the air feeding time, the piston 541 has a holeportion 542 of comparatively small diameter formed therein forcontrolling the time from the point at which the valve (544, 549) isopened and air begins to flow in reverse to the point at which the valveis closed. The hole portion 542 is configured such that the air can bemade to flow from one side to another side in accordance with thedifference between the pressure of the air at the first end (lower sidein the drawing) inside the chamber (volume chamber) with reference tothe piston 541 and the pressure of the air at the second end (upper sidein the drawing). As the configuration of an air feeding time adjustingmeans, the time from the point at which the valve (544, 549) is openedand the air begins to flow in reverse to the point at which the valve isclosed is determined by the opening diameter of the hole portion 542.

Yet further, the valve seat portion 549 at the first end (lower side inthe drawing) of the chamber (volume chamber) 543 is connected to a firstflow passage 547. The first flow passage 547 is also connected to theair tank. On the other hand, the second end (upper side in the drawing)of the chamber (volume chamber) 543 is connected to a second flowpassage 548. The second flow passage 548 is also connected to a dryingcontainer (non-illustrated) and is further connected via the dryingcontainer to an exhaust valve (non-illustrated) and a compressor(non-illustrated).

The compressed air is delivered from the second flow passage 548 intothe second end (upper side in the drawing) of the chamber (volumechamber) 543 with reference to the piston 541. The pressure of the airat the second end (upper side in the drawing) of the chamber (volumechamber) 543 with reference to the piston 541 then becomes greater thanthe pressure of the air at the first end (lower side in the drawing).The air at the second end (upper side in the drawing) of the chamber(volume chamber) 543 thus gradually flows into the first end (lower sidein the drawing) of the chamber (volume chamber) 543 via the hole portion542. The air thus accumulates in the first end (lower side in thedrawing) of the chamber (volume chamber) 543 and the pressure of the airat the first end (lower side in the drawing) increases gradually.

The pressure of the air at the first end (lower side in the drawing) ofthe chamber (volume chamber) 543 then gradually moves the piston 541 tothe second end (upper side in the drawing) against the urging force ofthe compression coil spring 545. When the piston 541 moves to the secondend (upper side in the drawing), the valve (544, 549) is put in the openstate. After the valve (544, 549) is opened, a set pressure is reachedat the air tank and the exhaust valve is opened by a pressure governor(non-illustrated). The compressed air from the second flow passage 548is thus discharged from the exhaust valve. The air from the air tankconnected to the first flow passage 547 then begins to flow in reverseto the second flow passage 548 via the valve (544, 549) and the secondend (upper side in the drawing) of the chamber (volume chamber) 543.

As shown in FIG. 31(B), the air feeding time adjusting function beginsto operate from the point at which the valve (544, 549) is opened andthe air begins to flow in reverse. Specifically, the pressure of the airat the second end (upper side in the drawing) of the chamber (volumechamber) 543 with reference to the piston 541 becomes lower than thepressure of the air at the first end (lower side in the drawing). Theair at the first end (lower side in the drawing) thus gradually flowsout to the second end (upper side in the drawing) via the hole portion542. The pressure of the air at the first end (lower side in thedrawing) thus decreases gradually. When the magnitude of the force bywhich the piston 541 is pressed by the pressure of the air at the firstend (lower side in the drawing) becomes less than the magnitude of theforce by which the compression coil spring 545 presses the piston 541,the piston 541 is gradually moved to the first end (lower side in thedrawing) by the urging force of the compression coil spring 545.

During this process, the valve (544, 549) is in the open state and theair from the first flow passage 547 continues to be delivered to thesecond flow passage 548 via the valve (544, 549) and the second end(upper side in the drawing) of the chamber (volume chamber) 543. When apredetermined time (for example, 30 seconds) elapses from the point atwhich the valve (544, 549) is opened and the air begins to flow inreverse, the valve element 544 contacts the valve seat portion 549 sothat the valve (544, 549) is switched to the closed state and the flowof air from the first flow passage 547 is stopped. It is configuredthat, as the air feeding time adjusting function, the air can be made toflow in reverse via the valve (544, 549) for the predetermined time (forexample, 30 seconds).

However, the configuration is such that in switching the valve (544,549) from the closed state to the open state in the stage before the airfeeding time adjusting function begins to operate, the air is made toflow into the first end (lower side in the drawing) of the chamber(volume chamber) 543 only via the hole portion 542. The switching of thevalve (544, 549) from the closed state to the open state thus requires atime (for example, of 30 seconds) that is substantially equal in lengthto the time (for example, of 30 seconds) during which the air feedingtime adjusting function is activated to switch from the open state tothe closed state.

In other words, in the valve device 540 that makes use of the time inwhich the air in the volume chamber at the first end (lower side in thedrawing) of the chamber (volume chamber) 543 with reference to thepiston 541 is exhausted, a time of substantially the same length as theexhausting time is required for putting the air into the volume chamberat the first end (lower side in the drawing).

Although the time required for regeneration of a drying agent differsvariously according to system and is determined by the opening diameterof the hole portion 542 in the present configuration, the time forfilling the volume chamber with air (time until the valve (544, 549) isopened) is also determined by the opening diameter of the hole portion542 in the present configuration. The timing of regeneration of thedrying agent is thus influenced by the air filling time and therefore, arequirement of rapid air filling and flexibility of time setting of theair feeding time adjusting function for the regeneration process cannotbe achieved at the same time. For example, if only 15 seconds areavailable as the time for filling with air, sufficient air fillingcannot be performed for activating the air feeding time adjustingfunction for 30 seconds and the air feeding time adjusting function isactivated incompletely for just 15 seconds. The drying agent cannot beregenerated sufficiently in this case.

The present invention has been made in view of such circumstances and afourth problem (object) thereof is to provide a regeneration valvedevice for an air dryer that takes into consideration the simultaneousachievement of the requirement of rapid air filling and flexibility oftime setting of the air feeding time adjusting function for the dryingagent regeneration process.

An air dryer captures, in its interior, the moisture and oil incompressed air discharged from an air compressor and in regenerating adrying agent, an exhaust valve is opened to discharge drain water, whichcontains oil, together with the compressed air through the exhaustvalve.

However, with a conventional configuration, a drying agent regeneratingoperation is executed by an air pressure signal for opening the exhaustvalve being output from a pressure governor when the air compressor isunloaded, that is, when the air pressure inside an air tank reaches apredefined upper limit value. The regeneration operation is thusexecuted when the condition is met, even in a location where thedischarge of drain water is undesirable in terms of sanitationmanagement, for example, in a food factory or a precision parts factory,and it is thus desired to avoid performing the drying agent regenerationin such a location where the discharge of drain water is undesirable.

A fifth object (problem) of the present invention is thus to provide acompressed air supply device for a vehicle by which the timing of adrying agent regeneration operation can be controlled easily.

In FIG. 31, the piston 541 has a large diameter portion on which theO-ring 546 is mounted and a small diameter portion at a vicinity of thevalve element. The large diameter portion and the small diameter portionslide while contacting the inner side, and the like, of the volumechamber 543 in this configuration. Sliding is performed at locationsthat differ in the magnitude of diameter and there is thus a possibilityfor axial deviation to occur in which the attitude of the piston 541inclines with respect to the direction of movement. There is then apossibility for increase of sliding load due to a twisting action causedby the axial deviation. Yet further, there is a possibility for therubber O-ring 546, and the like, which are generally mounted on thepiston 541 (including the shaft and other portions of small diameter),to degrade significantly rapidly due to the increase of sliding load.

The present invention has been made in view of such circumstances and asixth problem (object) thereof is to provide a valve device that takesinto consideration the sliding of a piston for performing opening andclosing of a valve having an air feeding time adjusting function and anair dryer that includes the valve device.

Means for Solving the Problems

To achieve the first objective, the present invention provides an airdryer including a supporting base, a drying agent container, and anouter cover. The supporting base includes an inlet for receivingcompressed air to be subject to a drying process and an outlet fordelivering the processed compressed air that has undergone the dryingprocess. The drying agent container is a container supported on thesupporting base, contains a drying agent in the interior, and enablesthe drying process to be performed by passing the compressed air fromthe inlet through the drying agent. The outer cover surrounds the outerside of the drying agent container on the supporting base and defines achamber for storing the compressed air between itself and the dryingagent container. The air dryer is characterized in that the supportingbase includes first and second mounting surfaces, which are oriented indifferent directions, and a plurality of inlets, which are oriented indifferent directions and receive the compressed air.

With this configuration, the supporting base includes the first andsecond mounting surfaces that are oriented in different directions andthe plurality of inlets that are oriented in different directions andreceive the compressed air. Therefore by selection of one of the firstand second mounting surfaces and any of the plurality of inlets, thevariation of combinations of the mounting surface and the inlet can beincreased and mounting of the air dryer on diverse mounting positionscan be performed easily with the same configuration. Also, improvementof the versatility and productivity of the air dryer is achieved becausethe air dryer of the same configuration can be mounted on diversemounting positions.

In this configuration, the first and second mounting surfaces may beformed on mutually adjacent surfaces among the side surfaces of thesupporting base, and the inlets may be collectively located at a cornerportion of the supporting base that is positioned away from the mountingsurfaces. With this configuration, the first and second mountingsurfaces are formed on mutually adjacent surfaces among the sidesurfaces of the supporting base and therefore the supporting base can beeasily changed in position with respect to and mounted on a mountingtarget. Also, the plurality of inlets are collectively located at thecorner portion of the supporting base that is positioned away from thefirst and second mounting surfaces and therefore in connecting piping tothe inlets, the piping connecting process can be performed readilywithout interference of the piping and the mounting target on which themounting surface is mounted.

The outlet may be located at a side surface of the supporting baseopposite from the first mounting surface, and a wet tank or a protectionvalve may be selectively mountable on the outlet. With thisconfiguration, the outlet for delivering the compressed air is providedat the side surface that differs from the first and second mountingsurfaces and a process of mounting equipment on the outlet can thus beperformed easily.

Further, the wet tank or the protection valve is selectively mountableon the outlet, so that the equipment mounted on the outlet can beselected in accordance with mounting conditions of the supporting baseand the arrangement of peripheral equipment, thereby enablingrealization of diverse air circuit layouts.

A plurality of planned opening portions may be provided incorrespondence to the inlets, and a hole may be formed in a plannedopening portion in accordance with mounting conditions of the supportingbase. With this configuration, it suffices to bore a hole in the plannedopening portion for the inlet to be actually used and working processesare thus reduced correspondingly and workability is improved. Further,with this configuration, a hole is not bored in a planned openingportion for an inlet that is not used and the process of closing offthis inlet is made unnecessary and air leakage from the inlet isprevented reliably.

A first aspect of the present invention for resolving the second problemis a silencer including an expansion chamber, having a plurality ofinner walls respectively facing a plurality of slits that are dischargeoutlets for drain and air from an exhaust valve in an air dryer thatperforms a drying process on compressed air, and a noise absorbingmaterial housing chamber connected to the expansion chamber and housinga noise absorbing material.

With the present aspect, the silencer for reducing air discharge noisefrom the exhaust valve in the air dryer that performs the drying processon compressed air has a configuration where the air discharged from theslits, which discharge the drain and air, hits different inner wallsinside the expansion chamber. That is, the discharged air from theexhaust valve is branched into a plurality of flow passages and hits theinner walls inside the expansion chamber under respectively differentconditions, thereby enabling the “noise range” in the process ofdischarge of air from the plurality of slits to be dispersed, and abetter silencing effect can thereby be obtained.

The plurality of inner walls respectively facing the plurality of slitsdoes not necessarily signify an embodiment where different inner wallscorrespond in a one-to-one manner with the plurality of slits, and inaddition to such an embodiment, for example, an embodiment where thereis not less than two facing slits (slit openings) with respect to oneinner wall is also included. That is, it suffices that there be presentan expansion chamber having a plurality of inner walls and a pluralityof slits that discharge air toward at least two inner walls.

A second aspect of the present invention is characterized in that, inthe first aspect, at least either the angles or the distances by whichthe air discharged from the plurality of slits hits the different innerwalls inside the expansion chamber differ.

This aspect is configured such that at least either the angles or thedistances by which the air discharged from the plurality of slits hitsthe different inner walls inside the expansion chamber differ andtherefore the above-described actions and effects of the second aspectare obtained even more effectively.

A third aspect of the present invention is characterized in that in thefirst and second aspects, the noise absorbing material is a porousmaterial.

With this aspect, the noise absorbing material is a porous material andan even better silencing effect is obtained by the silencing effect dueto the discharged air passing through numerous pores.

A fourth aspect of the present invention is characterized in that in anyone of the first to third aspects, a final discharge outlet thatdischarges the drain and the air to the exterior has a shape that opensonly vertically downward.

With this aspect, the final discharge outlet that discharges the drainand the air to the exterior has a shape that opens only verticallydownward and by the air discharge noise thus being emitted downward, theair discharge noise is made even more difficult to hear.

A fifth aspect of the present invention is characterized in that in anyone of the first to fourth aspects, at least the discharge outlet of theexhaust valve at which the slits are formed, the expansion chamber, andthe noise absorbing material housing chamber are formed integrally on abase member forming a base of the air dryer.

With the present aspect, at least the discharge outlet of the exhaustvalve at which the slits are formed, the expansion chamber, and thenoise absorbing material housing chamber are formed integrally on thebase member forming the base of the air dryer and therefore costreduction of the air dryer with silencer is achieved and the volumeoccupied by the silencer can also be reduced.

Also, by forming the components of the silencer integrally on the basemember forming the base of the air dryer, the strength is ensuredreadily and an even better silencing effect is obtained by making thedischarged air hit a rigid body.

A sixth aspect of the present invention is an air dryer that performs adrying process on compressed air and is characterized by the silenceraccording to any one of the first to fifth aspects that reduces airdischarge noise from an exhaust valve discharging drain generated by thedrying process. With the present aspect, the same actions and effects asthose of any one of the first to fifth aspects are obtained in the airdryer.

The first aspect of the present invention for resolving the thirdproblem provides a valve that discharges drain and air generated by adrying process in an air dryer that performs the drying process oncompressed air supplied from an air compressor. The valve is an exhaustvalve configured to receive the pressure of the compressed air suppliedfrom the air compressor in a valve closed state and to open whenreceiving a control command pressure from a pressure governor when thecompressed air reaches a predefined pressure and characterized by avalve body pressed in a valve opening direction by the pressure of thecompressed air and an urging means urging the valve body in a valveclosing direction against the pressure of the compressed air and havinga configuration where the valve closed state is maintained against thepressure of the compressed air by the urging force of the urging means.When the control command pressure is received from the pressuregovernor, the control command pressure opens the valve against theurging force of the urging means.

Unlike the conventional configuration, the present aspect is configuredsuch that the valve body of the exhaust valve has a structure of beingpressed not in the valve closing direction but in the valve openingdirection by the pressure of the compressed air supplied from the aircompressor. The valve closed state is maintained by the urging force ofthe urging means when the air compressor is in the loaded state andtherefore the piston forming the valve body is not required to be formedto a T-like shape that is large in diameter at an upper portion from thestandpoint of pressure receiving area as in the conventional art.

There is thus no need to ensure a large opening for housing the valvebody and a valve base, which thus has to be made large in diameterconventionally, can be made compact or the valve base itself is madeunnecessary. The need to arrange the valve body from several members dueto reasons of assembly is also eliminated and an integral configurationis made possible. By the above reasons, the structure of the exhaustvalve is simplified and cost reduction can also be achieved.

The second aspect of the present invention is characterized in that thevalve body is formed by a piston member, sliding in valve opening andclosing directions, and a valve element, contacting a valve seat, beingformed integrally and the valve seat is formed using a portion of a basemember forming a base of the air dryer.

With this configuration, the piston member, which slides in the valveopening and closing directions, and the valve element, which contactsthe valve seat, are formed integrally so that the valve that moves invertical directions is reduced in cost. Also, the valve seat is formedusing a portion of the base member of the air dryer; that is, the valveseat is integral to the base member so that the exhaust valve can bemade even simpler in structure to achieve cost reduction.

A third aspect of the present invention is an air dryer that performs adrying process on compressed air and is characterized by the exhaustvalve according to the first or second aspect that discharges either orboth of drain and air generated by the drying process.

With this aspect, the same first or second actions and effects describedabove are obtained in the air dryer.

To solve the fourth problem, a regeneration valve device for an airdryer according to the first aspect of the present invention ischaracterized by a chamber, a piston, a valve, an urging means, a holeportion, and an auxiliary flow passage. The chamber is located between adrying portion that performs a drying process on a compressed gassupplied from a gas compressor and a gas tank that stores the drycompressed gas that has undergone the drying process. The pressure ofthe gas acts on the chamber. The piston moves inside the chamber anddefines the interior of the chamber into a first end space on the sidecorresponding to the gas tank and a second end space on the sidecorresponding to the drying portion. The valve is put in a closed stateby the piston moving toward the first end and put in an open state bythe piston moving toward the second end. The urging means urges thepiston in the direction in which the valve is closed. The hole portionis formed in the piston and makes the gas flow from one side to anotherside in accordance with the difference between the pressure of the gasinside the first end space and the pressure of the gas inside the secondend space. The auxiliary flow passage has a restricting means thatallows the flow of gas in the direction from the second end space to thefirst end space of the chamber and restricts the flow of gas in thedirection from the first end space to the second end space in the flowpassage.

With this aspect, when the gas is delivered from the gas compressor intothe second end space inside the chamber, the gas delivered into thesecond end space can flow into the first end space inside the chambervia the hole portion and the auxiliary flow passage. Therefore incomparison to the configuration where the gas flows in only via the holeportion (see FIG. 31), the amount flowing in per unit time is increased.Consequently, the time required for accumulating the gas in the firstend space in the chamber to move the piston to the second end to switchthe valve to the open state is shortened. That is, the valve is put inthe open state when making gas of a sufficient amount flow into thefirst end space in the chamber and there is thus no possibility of theair feeding time adjusting function starting to operate in an incompletestate.

On the other hand, after the valve is switched to the open state and thedry compressed gas in the gas tank begins to flow in reverse, the gas inthe first end space in the chamber flows out gradually to the second endspace via the hole portion. The pressure in the first end space in thechamber is decreased by the outflow of the gas. In this process, theurging force of the urging means moves the piston to the first end andby this movement of the piston, the valve is put in the closed state.The dry compressed gas in the gas tank can thus be made to flow inreverse for just a predetermined time.

That is, in the configuration for controlling the length of the time ofreverse flow by the hole portion, the requirement of rapid air fillingand flexibility of time setting of the air feeding time adjustingfunction for a drying agent regeneration process is achieved at the sametime.

The second aspect of the present invention is characterized by thefollowing configuration. In the first aspect, the auxiliary flow passageis formed by a clearance between the outer peripheral surface of aflange portion of the piston and the inner peripheral surface of thechamber. The restricting means is formed by a cup seal housed in arecessed portion formed along the outer peripheral surface of the flangeportion such that an opening portion faces the first end space. The cupseal enlarges and reduces the opening portion by elastic deformation.The gas flows into the first end space via the hole portion andadditionally via the auxiliary flow passage due to the opening portionof the cup seal reducing to open the clearance when the gas flows fromthe second end space in the chamber into the first end space. The gasflows out to the second end space only via the hole portion due to theopening portion of the cup seal enlarging to close the clearance whenthe gas flows out from the first end space in the chamber to the secondend space.

With this aspect, in addition to the same actions and effects as thefirst aspect, a check valve function is achieved by a simple structureand at low cost.

The third aspect of the present invention is characterized by thefollowing configuration. In the first or second aspect, the gas isdelivered from the drying portion to the second end space in thechamber. The gas is delivered into the second end space flowing into thefirst end space in the chamber. The pressure in the first end space inthe chamber increases. The piston is moved by the pressure to the secondend against the urging force of the urging means and the valve is put inthe open state by the movement of the piston. By the gas in the firstend space in the chamber flowing out to the second end space via thehole portion and the pressure in the first end space in the chamberdecreasing due to the outflow of the gas, the urging force of the urgingmeans moves the piston to the first end and the valve is put in theclosed state by the movement of the piston.

With this aspect, in addition to the same actions and effects as thefirst or second aspect, the valve can be put in the open state byfeeding the gas from the drying portion into the second end space insidethe chamber. Also, the time from the point at which the gas begins toflow out to the point at which the valve is switched to the closingstate can be adjusted by means of the opening diameter of the holeportion.

An air dryer according to the fourth aspect of the present invention isan air dryer that includes a drying portion having a regenerable dryingagent and a regeneration valve device connected to a first end of a flowpassage in the drying portion. The air dryer of the fourth aspect ischaracterized by the following configuration: The regeneration valvedevice is the regeneration valve device according to any one of thefirst to third aspects, a gas compressor and a gas discharge portion areconnected to the second end of the flow passage in the drying portion.The valve of the regeneration valve device is put in the open state bythe gas being delivered by the gas compressor to the first end spaceinside chamber via the hole portion and the auxiliary flow passage ofthe regeneration valve device. By the gas discharge portion being put inan atmosphere released state, the dry compressed gas inside the gas tankis delivered to the drying portion via the valve of the regenerationvalve device and discharged from the gas discharging portion.

With the present aspect, the air dryer includes the regeneration valvedevice of any one of the first to third aspects. The same actions andeffects as any one of the first to third aspects can thus be obtained inthe air dryer. Also, by the gas discharge portion being put in theatmosphere released state, the air feeding time adjusting functionbegins to operate and the dry compressed gas inside the gas tank can beused for regeneration of the drying agent for just a predetermined time.

To achieve the fifth object, the compressed air supply device for avehicle according to the first aspect of the present invention ischaracterized in that the compressed air supply device for a vehicle,which includes an air compressor installed in a vehicle and an air dryerremoving moisture and other foreign matter contained in the compressedair discharged from the air compressor and supplies the compressed airthat has passed through the air dryer to a load of the vehicle. Thecompressed air supply device includes a regenerating means regeneratinga drying agent in the air dryer at a predetermined timing, a vehiclespeed detecting means detecting the vehicle speed of the vehicle, and aregeneration inhibiting means inhibiting the regeneration of the dryingagent regardless of the predetermined timing if the detected vehiclespeed is slower than a predetermined reference speed.

The second aspect of the present invention is characterized in that inthe first aspect, the regenerating means includes an exhaust valvearranged in the air dryer, a regeneration solenoid valve applying an airpressure for control to the exhaust valve via a control line, and aregeneration control means opening the regeneration solenoid valve atthe predetermined timing to apply the air pressure to the exhaust valveto open the exhaust valve and perform regeneration control of the dryingagent in the air dryer.

Also, the third aspect of the present invention is characterized in thatin the first or second aspect, a humidity sensor is located downstreamof the drying agent in the compressed air supply device for a vehicle.If the humidity level detected by the humidity sensor indicates ahumidity level not less than a threshold set in advance, theregeneration of the drying agent is forcibly executed even if theregeneration of the drying agent is inhibited.

Also, the fourth aspect of the present invention is characterized inthat in the first or second aspect, a humidity sensor is locateddownstream of the drying agent. When the humidity level detected by thehumidity sensor indicates a humidity level not less than a threshold setin advance, the regeneration of the drying agent is put on standby untilthe inhibition of regeneration of the drying agent is cancelled.

To achieve the sixth problem, the valve device according to the firstaspect of the present invention is a valve device that opens and closesa bypass flow passage bypassing a flow passage of gas between a gascompressor and a gas tank storing the gas supplied from the gascompressor. The valve device is characterized by a volume chamber and afirst valve. The internal pressure of the volume chamber is increased bygas being supplied from at least one of either of the gas compressor andthe gas tank and is decreased by gas flowing out over a predeterminedtime from a hole portion in accompaniment with pressure reduction on theside corresponding to the gas compressor. The first valve is incommunication with the volume chamber, opens the bypass flow passage dueto pressure reduction on the side corresponding to the gas compressor ina state where a predetermined pressure is reached at the volume chamber,and thereafter closes the bypass flow passage due to reduction of theinternal pressure of the volume chamber. The first valve is configuredto open and close the bypass flow passage by a piston sliding inside acylinder portion formed independently of the volume chamber.

With the present aspect, the cylinder portion is arranged independentlyof the volume chamber. The volume chamber is required to accumulate apredetermined amount of gas and must thus be made rather large in size.On the other hand, the cylinder portion is not required to accumulate apredetermined amount of gas like the volume chamber and therefore doesnot need to be made large in size. The diameter of the piston thus doesnot have to be made large. The piston can thus be formed so thatlocations of the same diameter of the piston contact and slide along theinner side of the cylinder portion.

Consequently, axial deviation, in which the attitude of the pistoninclines with respect to the movement direction when locations thatdiffer largely in diameter contact and slide, is prevented fromoccurring. Also, increase of the sliding load due to a twisting actiondue to axial deviation is prevented. Yet further, the possibility for arubber piston ring, which is generally mounted on the piston, to degradedue to the increase of sliding load is reduced. The valve device canthereby be improved in durability.

The second aspect of the present invention is characterized in that, inthe first aspect, at least three ring-shaped sealing members arearranged at appropriate intervals along the movement direction of thepiston on the outer periphery of the piston to partition the interior ofthe cylinder portion into at least four portions of first to fourthspaces in that order in the movement direction of the piston. A firstopening in communication with the gas compressor side flow passage inthe bypass flow passage and a second opening in communication with thegas tank side flow passage in the bypass flow passage are formed at apredetermined interval in the movement direction of the piston in theinner wall of the cylinder portion. The first space is a space that isconstantly in communication with the volume chamber regardless of theposition of the piston. The fourth space is a space having the firstopening at its inner side regardless of the position of the piston. Thesecond space is a space that is constantly put in communication with thefourth space by a communication passage formed inside the piston. Thethird space is a closed space. The piston is urged in the direction ofclosing the first valve by an urging means. The first valve is put inthe closed state by a state where the second opening is positionedinside the third space being maintained by balancing of the pressureacting on the piston in the first space and the pressure acting on thepiston in the fourth space in the state where the gas is supplied fromthe gas compressor. The first valve is put in the open state when, dueto pressure reduction on the side corresponding to the gas compressor,the pressure acting on the piston in the first space overcomes thepressure acting on the piston in the fourth space to move the pistonuntil the second opening is positioned inside the second space. Thefirst valve is thereafter put in the closed state when, due to reductionof the internal pressure of the volume chamber, the pressure acting onthe piston in the first space decreases and the piston is returned bythe urging force of the urging means until the second opening ispositioned inside the third space.

With the present aspect, in addition to the same actions and effects asthe first aspect, the gas pressure in the space at the first end insidethe cylinder portion is balanced with the gas pressure in the space atthe second end before the outflow of gas from the hole portion begins.In this state, the position of the piston is stabilized with a spring ofsmall force.

Also, by generation of a difference between the gas pressure in thefirst space inside the cylinder portion and the gas pressure in thefourth space, the piston is moved and the first valve is changed fromthe open state to the closed state.

Yet further, when the predetermined time elapses, the gas pressure inthe first space inside the cylinder portion and the gas pressure in thefourth space are balanced again. In this state, the piston is configuredto be moved by the urging force of the urging means.

Consequently, the urging force of a spring, which is an example of theurging means, may be made comparatively small. Also, spring relaxation,in which a spring having a comparatively strong urging force loses itsurging force, does not have to be considered because the urging force ofthe spring is made comparatively small.

Also, the first valve is put in the open state by moving the pistonuntil the second opening is positioned inside the second space and thefirst valve is put in the closed state by the piston being returneduntil the second opening is positioned inside the third space.Consequently, the switching can be performed with a simpleconfiguration.

The third aspect of the present invention is characterized by, in thefirst or second aspect, a second valve for filling gas into the volumechamber and a third valve for discharging the gas from the volumechamber via the hole portion are included.

With the present aspect, in addition to the same actions and effects asthe first and second aspects, the volume chamber can be filled with gasin a short time in comparison to a configuration not having the secondvalve and the third valve.

The fourth aspect of the present invention is characterized in that inthe third aspect, the gas discharged from the volume chamber via thehole portion is released to the atmosphere.

With the present aspect, in addition to the same actions and effects asthe third aspect, the gas in the volume chamber is discharged to alocation without residual pressure and the gas pressure in the volumechamber can thus always be returned to the original gas pressure.Consequently, the closed state is returned to reliably after the openstate has been attained once. Also, variation of the length of timerequired to return to the closed state from the point at which the openstate is attained is made small and the length of time is stabilized.

The air dryer according to the fifth aspect of the present invention isan air dryer that includes a drying portion having a regenerable dryingagent and a regeneration valve device connected to a first end of a flowpassage in the drying portion. The air dryer is characterized in thatthe regeneration valve device is the valve device according to any oneof the first to fourth aspects, the drying portion is located betweenthe regeneration valve device and both the gas compressor and the gasdischarge valve. The drying agent is dried using the gas in the gas tankthat flows in reverse when the gas discharge valve is opened and thefirst valve opens the bypass flow passage.

With the present aspect, the regeneration valve device of the air dryeris the valve device of any one of the first to fourth aspects. The sameactions and effects as any one of the first to fourth aspects can thusbe obtained in the air dryer.

The valve device according to the sixth aspect of the present inventionis characterized by a volume chamber, an intake inlet and an exhaustoutlet provided in the volume chamber, and a valve in communication withthe volume chamber and opening or closing for a predetermined time inaccordance with a change of pressure in the volume chamber.

Gas (air) of high pressure is contained in the volume chamber. The highpressure gas is supplied to the intake inlet from the compressor. Thehigh pressure gas supplied to the volume chamber is discharged from theexhaust outlet. The volume chamber is in communication with the valve. Apiston type, ball valve type, or diaphragm type may be used as thevalve.

For example, with the piston type, the high pressure gas from the volumechamber is made to flow into a chamber at a first side with respect tothe movement direction of the piston and a spring, rubber, or otherurging means is located in a chamber at a second side.

While the piston is pushed by the high pressure gas, the piston is movedtoward the urging means against the force of the urging means. As thehigh pressure gas inside the volume chamber is vented from the exhaustoutlet, the piston is pushed by the force of the urging means and movedto the side opposite to the urging means.

A plurality of flow passages are put in communication with the movementspace of the piston, and communication and closure among the flowpassages is selected according to the piston movement.

For example, the valve may be configured such that the flow passages areput in communication when the volume chamber is filled with the highpressure gas and the piston is on the side corresponding to the urgingmeans and the flow passages are closed by the piston while the piston ismoving to the side opposite to the urging means as the high pressure gasis vented from inside the volume chamber.

In contrast, the valve may be configured such that the flow passages areclosed by the piston when the volume chamber is filled with the highpressure gas and the piston is on the side corresponding to the urgingmeans, and the flow passages are put in communication while the pistonis moving to the side opposite to the urging means as the high pressuregas is vented from inside the volume chamber.

The time of pressure reduction in the volume chamber can be adjusted byadjusting the size of the exhaust outlet of the volume chamber and themovement time of the piston can thus be adjusted to control theopening/closing time of the valve.

Also, the exhaust outlet and the intake inlet of the volume chamber maybe a single common port and a solenoid valve, and the like, may be usedon the side corresponding to the compressor to perform the filling ofthe volume chamber with the high pressure gas and the release toatmosphere. In place of the high pressure gas, the volume chamber may befilled with a vacuum pressure gas by connecting a vacuum pump (vacuumsource) to the intake inlet.

With a vacuum pressure gas, gas of the atmosphere, and the like, flowsinto the volume chamber from the exhaust outlet of the volume chamber.The volume chamber is in communication with the valve. As with the highpressure gas, a piston type, ball valve type, or diaphragm type may beused as the valve.

For example, with the piston type, a chamber at a first side withrespect to the movement direction of the piston is put in communicationwith the volume chamber and set to vacuum pressure, and a spring,rubber, or other urging means is located in the chamber at the firstside.

The second side of the piston is pushed by the atmospheric pressure orother pressure higher than the vacuum pressure gas and the piston isthus moved toward the urging means against the force of the urgingmeans. As the vacuum pressure inside the volume chamber increases, thepiston is pushed by the force of the urging means and is moved to theside opposite to the urging means.

A plurality of flow passages are put in communication with the movementspace of the piston and communication and closure among the flowpassages can be selected according to the piston movement.

For example, the valve may be configured such that the flow passages areput in communication when the volume chamber is at the vacuum pressureand the piston is at the urging means side and the flow passages areclosed by the piston when the pressure inside the volume chamberincreases and the piston moves to the side opposite to the urging means.

In contrast, the valve may be configured such that the flow passages areclosed by the piston when the volume chamber is at the vacuum pressureand the piston is on the side corresponding to the urging means, and theflow passages are put in communication while the piston is moving to theside opposite to the urging means as the pressure inside the volumechamber increases.

The time of pressure increase in the volume chamber can be adjusted byadjusting the size of the exhaust outlet of the volume chamber and themovement time of the piston can thus be adjusted to control theopening/closing time of the valve.

Also, the exhaust outlet and the intake inlet of the volume chamber maybe a single common port and a solenoid valve, and the like, may be usedon the side corresponding to the vacuum pump to perform vacuum drawingand release to atmosphere of the volume chamber.

The compressed air supply system device according to the seventh aspectof the present invention is characterized by the followingconfiguration. An air dryer is located in a supply flow passage betweena gas compressor and a gas tank storing a gas supplied from the gascompressor. A check valve allowing the flow of gas from on the sidecorresponding to the air dryer to on the side corresponding to the gastank is located in the supply passage between the gas tank and the airdryer. An intake inlet and an exhaust outlet are provided in a volumechamber. The system includes a valve in communication with the volumechamber and opening and closing in accordance with the pressure insidethe volume chamber. The valve is provided for opening and closing apurge flow passage that puts a point between the gas tank and the checkvalve and a point between a drying agent of the air dryer and the checkvalve in communication.

The intake inlet of the volume chamber is put in communication with thesupply flow passage between the gas compressor and the drying agent ofthe air dryer or the supply flow passage between the drying agent of theair dryer and the check valve, and the interior of the volume chamber isfilled with the high pressure gas from the gas compressor. Also, theintake inlet of the volume chamber may be put in communication with thesupply flow passage between the check valve and the gas tank via avalve. By being put in communication via the valve, the high pressuregas inside the gas tank is prevented from being vented more thannecessary from the exhaust outlet of the volume chamber.

The valve has an open configuration to supply the high pressure gas tothe volume chamber until a predetermined amount or a predeterminedpressure is attained and a piston type, diaphragm type, ball valve type,or solenoid type may be used. The valve may be located in an intake flowpassage to the intake inlet of the volume chamber that is incommunication with the supply flow passage between the gas compressorand the drying agent of the air dryer or the supply flow passage betweenthe drying agent of the air dryer and the check valve. Reverse flow ofthe high pressure gas inside the volume chamber from the intake flowpassage to on the side corresponding to the supply flow passage canthereby be prevented. As the supply source of the high pressure gas tothe volume chamber, supplying can be performed by a second gascompressor that is independent of the gas compressor.

A piston type, ball valve type, or diaphragm type may be used as thevalve.

For example, with the piston type, the high pressure air from the volumechamber flows into a chamber at a first side with respect to themovement direction of the piston and a spring, rubber, or other urgingmeans is located in the chamber at a second side.

While the piston is pushed by the high pressure air from inside thevolume chamber, the piston is moved toward the urging means against theforce of the urging means. As the high pressure air inside the volumechamber is vented from the exhaust outlet, the piston is pushed by theforce of the urging means and is moved to the side opposite to theurging means.

The movement space of the piston is put in communication with a purgeflow passage in communication with the supply flow passage between thecheck valve and the gas tank and a purge flow passage in communicationwith the supply flow passage between the drying agent of the air dryerand the check valve.

With the two purge flow passages in communication with the movementspace of the piston, communication and closure is selected according tothe piston movement. For example, the valve may be configured such thatthe purge flow passages are put in communication when the volume chamberis filled with the high pressure air and the piston is on the sidecorresponding to the urging means and the flow passages are closed bythe piston while the piston is moving to the side opposite to the urgingmeans as the high pressure air is vented from inside the volume chamber.

In contrast, the valve may be configured such that the flow passages areclosed by the piston when the volume chamber is filled with the highpressure air and the piston is on the side corresponding to the urgingmeans, and the flow passages are put in communication while the pistonis moving to the side opposite to the urging means as the high pressureair is vented from inside the volume chamber.

Also, the time of pressure reduction in the volume chamber can beadjusted by adjusting the size of the exhaust outlet of the volumechamber using a throttle, and the like, and the movement time of thepiston can thus be adjusted to control the opening/closing time of thevalve.

Instead of being released to the atmosphere, the exhaust outlet of thevolume chamber may be put in communication with the supply flow passagebetween the check valve and the gas compressor or with the purge flowpassage from the valve to on the side corresponding to the air dryer.The volume chamber can thereby be put in communication with theatmosphere in linkage with the releasing of the supply flow passage orthe purge flow passage to the atmosphere by purging of the air dryer andthe purging time of the air dryer is adjusted by a simpler structure.

Also, if the time for high pressure gas filling by the throttle forexhausting time adjustment of the volume chamber does not present aproblem, the exhaust outlet and intake inlet of the volume chamber maybe a common port (hole). The volume chamber may be arranged as a valvenot only for high pressure gas but also for vacuum pressure.

Effects of the Invention

With the present invention, the supporting base includes the first andsecond mounting surfaces that are oriented in different directions andthe plurality of inlets that are oriented in different directions andreceive the compressed air, and therefore by selection of one of thefirst and second mounting surfaces and any of the plurality of inlets,the variation of combinations of the mounting surface and the inlet isincreased and mounting of the air dryer on diverse mounting positionscan be performed easily with the same configuration. Also, improvementof the versatility and productivity of the air dryer is achieved becausethe air dryer of the same configuration can be mounted on diversemounting positions.

Further, with the present invention, the regeneration inhibiting meansthat inhibits the regeneration of the drying agent regardless of thepredetermined timing if the detected vehicle speed is slower than thereference speed is included. The timing of the drying agent regenerationoperation can thus be controlled easily based on the vehicle speed, andthe regeneration operation is suppressed at locations, for example,within factory premises, where the traveling speed is restricted and thedischarge of drain water is undesirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of an air circuit using an air dryeraccording to the present embodiment;

FIG. 2 shows the outer appearance of the air dryer, with (A) being aplan view, (B) being a front view, and (C) being a bottom view;

FIG. 3 is a cross-sectional view taken along line of FIG. 2A;

FIG. 4 is a view taken along line IV-IV of FIG. 2C;

FIG. 5 shows the outer appearance of the air dryer, with (A) being arear view, (B) being a left side view, and (C) being a right side view;

FIG. 6 shows a mode of mounting of the air dryer, with (A) being adiagram of a state of mounting on a rear surface of a supporting baseand (B) being a diagram of a state of mounting on a right side surfaceof the supporting base;

FIG. 7 is a cross-sectional view of a portion of an air dryer and asilencer according to the present invention;

FIG. 8 is a perspective view of the silencer according to the presentinvention, with (A) showing the silencer as viewed from below and (B)showing a state where a lid member forming the silencer is opened;

FIG. 9 is a plan view of the state where the lid member forming thesilencer according to the present invention is opened;

FIG. 10 is a cross-sectional view of an exhaust valve according to thepresent invention (valve closed state);

FIG. 11 is a cross-sectional view of the exhaust valve according to thepresent invention (valve open state);

FIG. 12 is a diagram of a piping of a vehicle that includes a valvedevice according to the present embodiment;

FIG. 13 is a schematic cross-sectional view of the valve deviceaccording to the present embodiment (closed state);

FIG. 14 is a cross-sectional view illustrating an operation of the valvedevice according to the present embodiment (start of air inflow);

FIG. 15 is a cross-sectional view illustrating an operation of the valvedevice according to the present embodiment (open state (reverse flow));

FIG. 16 is a cross-sectional view illustrating an operation of the valvedevice according to the present embodiment (during operation of an airfeeding time adjusting function);

FIG. 17 is a diagram of a configuration of a compressed air supplysystem according to the present embodiment;

FIG. 18 is a flowchart of a regeneration inhibiting operation procedure;

FIG. 19 is a schematic view of a piping of an air processing system thatincludes a valve device according to the present embodiment;

FIG. 20 is a schematic cross-sectional view of the valve deviceaccording to the present embodiment;

FIG. 21 is a cross-sectional view illustrating an operation of the valvedevice according to the present embodiment (start of air inflow);

FIG. 22 is a cross-sectional view illustrating an operation of the valvedevice according to the present embodiment (immediately after opening);

FIG. 23 is a cross-sectional view illustrating an operation of the valvedevice according to the present embodiment (during operation of an airfeeding time adjusting function);

FIG. 24 is a schematic cross-sectional view of a valve device accordingto an additional embodiment;

FIG. 25 is a cross-sectional view illustrating an operation of the valvedevice according to the additional embodiment (start of air inflow);

FIG. 26 is a cross-sectional view illustrating an operation of the valvedevice according to the additional embodiment (immediately afteropening);

FIG. 27 is a cross-sectional view illustrating an operation of the valvedevice according to the additional embodiment (during operation of anair feeding time adjusting function);

FIG. 28 is a cross-sectional view illustrating an operation of a valvedevice according to another additional embodiment;

FIG. 29 is a cross-sectional view illustrating an operation of a valvedevice according to the additional embodiment of FIG. 28;

FIG. 30 is a cross-sectional view of an exhaust valve according to aconventional art; and

FIG. 31 illustrates a conventional valve device, with (A) and (B) beingcross-sectional views thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of the present invention for achieving the firstobject will now be described with reference to the drawings.

FIG. 1 is a circuit diagram of an example of an air circuit using an airdryer according to the present embodiment. The air circuit 1 includes anair dryer 10, an air compressor 3 is connected to an inlet 14 of the airdryer 10, and pressurized air is supplied from the air compressor 3. Aprotection valve 5 is connected to an outlet 16 of the air dryer 10, andair tanks 6, 7, 8, and 9 are connected respectively to four exhaustports of the protection valve 5. Brake circuits (service brake circuitsand a parking brake circuit) and compressed-air-driven accessories (hornand clutch driving mechanisms, and the like) of a vehicle arerespectively connected to the air tanks 6 to 9, and the brake circuitsand the accessories are driven by the compressed air being supplied fromthe corresponding air tanks 6 to 9. The protection valve 5 integrallyincludes a plurality of pressure protection valves respectivelycorresponding to the air tanks (brake circuits) 6 to 9 and systemsrespectively including the air tanks 6 to 9 are made independent of eachother. Therefore, the protection valve 5 functions in a manner such thatwhen the pressure of the compressed air in any of the air tanks 6 to 9decreases (when pressure loss occurs), the pressure protection valvecorresponding to the air tank is closed to protect the other air tanks(that is, the brake circuits) in which pressure loss has not occurred.

FIG. 2 shows three views of the air dryer 10, with (A) being a planview, (B) being a front view, and (C) being a bottom view.

As shown in FIG. 2B, the air dryer 10 includes a supporting base 12positioned at a bottom portion and a dryer main body 13 supported on thesupporting base 12. The supporting base 12 is a metal molded part madeof aluminum or an alloy thereof. In the present configuration, thesupporting base 12 is provided with a first inlet 14A and a second inlet14B, which receive compressed air to be subject to a drying process. Thefirst inlet 14A and the second inlet 14B are put in communication insidethe supporting base 12 and are located in the supporting base 12 so asto be oriented in different directions. Specifically, the first inlet14A is formed on a front surface 120 of the supporting base 12 as shownin FIGS. 2A and 2B and the second inlet 14B is formed on a left sidesurface 121 of the supporting base 12 as shown in FIGS. 2A and 2C.Accordingly, in performing a process of connecting a supply piping forsupplying the compressed air to the air dryer 10, it suffices to make aconnection with one of either of the first inlet 14A and the secondinlet 14B, thereby facilitating the routing of the supply piping andenabling the piping connecting process to be performed easily.

Further, as shown in FIG. 2A, the first inlet 14A and the second inlet14B are collectively located at a corner portion, at which the frontsurface 120 and the left side surface 121 of the supporting base 12intersect and which is positioned away from a rear surface 122 and aright side surface 123 of the supporting base 12, which function asmounting surfaces to be described below. Accordingly, in connecting thesupply piping to the first inlet 14A or the second inlet 14B, the supplypiping connecting process can be performed readily without interferenceof the supply piping with a member (for example, a vehicle body frame)that is to be a mounting target on which a mounting surface is mounted.

Also, as shown in FIG. 2B, a control air inlet 15 and a first outlet 16Aare arranged in lateral alignment with the first inlet 14A on the frontsurface 120 of the supporting base 12, and a flange 161 for mounting ofthe protection valve 5 is formed at a periphery of the first outlet 16A.

In the present configuration, a second outlet in communication with thefirst outlet 16A is provided and this will be described below.

The internal configuration of the air dryer 10 will now be described.FIG. 3 is a cross-sectional view taken along line III-III of FIGS. 2Aand 4 is a cross-sectional view taken along line IV-IV of FIG. 2C.

As shown in FIG. 3, the supporting base 12 integrally includes aprojecting portion 12A at the bottom surface and includes an inner ringportion 124 and an outer ring portion 126, which are concentric at theupper surface. The inner ring portion 124 is formed to be higher thanthe outer ring portion 126. Over the interval between the inner ringportion 124 and the outer ring portion 126, the upper surface of thesupporting base 12 is recessed largely so as to form a ring-shaped space128 thereat. As shown in FIG. 4, the ring-shaped space 128 is put incommunication with a lateral hole 111, extending substantiallyhorizontally inside the projecting portion 12A, through vertical holes110, extending downward from the ring-shaped space 128, and the lateralhole 111 is in communication with the second inlet 14B. Further, one ofthe vertical holes 110 is in communication with the first inlet 14A. Thering-shaped space 128 is thereby used as a space in which the compressedair, flowing into the supporting base 12 through the first inlet 14A orthe second inlet 14B, is temporarily stored.

The upper surface of the supporting base 12 surrounded by the inner ringportion 124 is also recessed largely to form a columnar inner space 129.The inner space 129 is put in communication with the interior of thedryer main body 13 by the inner ring portion 124 penetrating into thedryer main body 13 and is used as a space for storing the compressed airfor which the drying process has ended.

As shown in FIG. 4, the inner space 129 is put in communication with thefirst outlet 16A through a communicating hole 112 extending from theinner space 129. Also, as shown in FIG. 3, the inner space 129 is put incommunication with a purge opening 20, provided in the left side surface121 of the supporting base, through a purge hole 113. For example, apurge tank 45 (see FIG. 6) having a function of regenerating a dryingagent may be connected to the purge opening 20.

As shown in FIG. 3, the dryer main body 13 includes a drying agentcontainer 50 and an outer cover 70, which are positioned on thesupporting base 12. The drying agent container 50 is a container thatcontains a granular drying agent 58 in the interior and a lower portion51 is formed to be smaller in diameter than an upper portion 52. Afilter element 57, which removes oil and dust in air, is located at aperiphery of the lower portion 51. The outer cover 70 surrounds theouter side of the drying agent container 50 and defines a chamber 75 forstoring compressed air between itself and the drying agent container 50.The large diameter upper portion 52 is formed to be slightly smallerthan the inner diameter of the outer cover 70 and a gap between theseserves as an air flow passage. A lower lid 60 that holds the filterelement 57 is fixed to a lower portion of the outer cover 70, and thelower lid 60 includes a fitting hole 100 in which the inner ring portion124 of the supporting base 12 is fitted and a plurality of smalldiameter hole portions 101 formed in a periphery of the fitting hole 100and being in communication with the ring-shaped space 128.

An upper lid 61 is provided at an upper portion of the drying agentcontainer 50. An opening 107, which puts the chamber 75 and the dryingagent container 50 in communication, is formed in the upper lid 61. Acheck valve 62, which closes the opening 107, is arranged at the upperlid 61. The check valve 62 is urged to be in close contact with a lowersurface 105 of the upper lid 61 by a spring member 63 fixed to an innerupper surface 103 of the outer cover 70.

The compressed air to be subject to the drying process flows into thering-shaped space 128 from the first inlet 14A or the second inlet 14Band through the lateral hole 111 and the vertical holes 110 of thesupporting base 12. Then from the ring-shaped space 128, the compressedair flows into the dryer main body 13 through the small diameter holeportions 101 and compressor oil and dust are removed by the filterelement 57. The compressed air from which the oil, and the like, havebeen removed flows into the drying agent container 50 by the check valve62 opening and is dehumidified by passing through the drying agent 58inside the drying agent container 50. The dehumidified and driedcompressed air reaches the protection valve 5 through the inner space129, the communicating hole 11, and the first outlet 16A and is storedin the external air tank 6, 7, 8, and 9 through the protection valve 5.

In accompaniment with such a drying process, drain containing moisture,compressor oil, and dust is generated. The air dryer 10 includes a drainvalve 90 for discharging such drain. As shown in FIG. 4, the drain valve90 is located inside a drain valve housing hole 115 intersecting thelateral hole 111 and includes a control piston 92, which is integral toa valve member. The control piston 92 receives a force due to a valvespring 94 and a force in accordance with the pressure in a controlchamber 96. A control command pressure from a pressure governor 40 (FIG.3) built into the supporting base 12 is applied to the control chamber96. As shown in FIG. 3, the pressure governor 40 includes a piston 41that moves in accordance with a pressure change of the air pressureinside an air tank (that is, the pressure of the dried compressed airdelivered from the outlet). The pressure governor 40 opens and closes avalve in accordance with the movement of the piston 41 to maintain theair pressure inside air tank within a predefined pressure range. Whenthe pressure governor 40 opens the valve, it outputs the control commandpressure to the control chamber 96 of the drain valve 90. When thecontrol command pressure is output from the pressure governor 40, thecontrol piston 92 moves and opens the drain valve 90. In accordance withthe opening and closing of the drain valve 90, the drain containingmoisture and oil is discharged, along with compressed air, to theexterior through an exhaust space 116 formed in the projecting portion12A. To reduce the noise accompanying the discharge, a silencer 117 isprovided in the exhaust space 116.

An air dryer such as described above is generally mounted in a narrowspace of a vehicle. In many cases, this space differs according to thevehicle model on which the air dryer is to be mounted. Therefore withthe conventional air dryer, for each vehicle on which the air dryer isto be mounted, a process of designing positions of a mounting portionand an inlet for compressed air that are in accordance with a mountingposition in the vehicle and forming the mounting portion and the inleton a supporting base is performed. The air dryer thus has problems ofbeing poor in versatility and also being poor in productivity.

To resolve the above, the supporting base 12 of the air dryer 10according to the present configuration includes a first mounting surfaceand a second mounting surface that are oriented in different directions.Specifically, as shown in FIGS. 5A and 5C, first mounting portions 31are formed on the rear surface 122 of the supporting base 12 as thefirst mounting surface and second mounting portions 32 are formed on theright side surface 123 as the second mounting surface adjacent to therear surface 122.

The first mounting portions 31 are provided in a triangular formationsurrounding a periphery of a rectangular member 43 provided at the rearsurface 122 of the supporting base 12, and threaded holes in whichfixing bolts are screwed are formed in the first mounting portions 31.On the other hand, the second mounting portions 32 are formed in atriangular formation surrounding a periphery of the pressure governor40, and threaded holes in which fixing bolts are screwed are also formedin the second mounting portions 32 as well. As shown in FIG. 2B, withthe second mounting portions 32, end surfaces of the second mountingportions 32 are located at positions lower than the pressure governor 40and therefore when mounting the air dryer 10 using the second mountingportions 32, collar members 32A (FIG. 6), through which fixing boltspenetrate, may be located between a vehicle body frame 80 (FIG. 6) orother mounting target member and the second mounting portions 32.

The second outlet 16B is formed in a corner portion of the right sidesurface 123 of the supporting base 12 that intersects the front surface120, and the second outlet 16B is in communication with the first outlet16A inside the supporting base 12. For example, a wet tank 46 (see FIG.6) having a function of removing and accumulating moisture and oil in asimplified manner by expansion of the compressed air may be connected tothe second outlet 16B.

Modes of mounting the air dryer 10 will now be described.

FIG. 6A is a diagram of a state of mounting the air dryer 10 on thevehicle body frame 80 using the rear surface 122 of the supporting base12 and FIG. 6B is a diagram of a state of mounting the air dryer 10 onthe vehicle body frame 80 using the right side surface 123 of thesupporting base 12.

In FIGS. 6A and 6B, the vehicle body frame 80 is a frame of highrigidity that extends in the front/rear direction of a vehicle and theair dryer 10 is generally mounted on a side surface of the vehicle bodyframe 80 in many cases.

When as shown in FIG. 6A, the air dryer 10 is mounted on the vehiclebody frame 80 via the first mounting portions 31 provided on the rearsurface 122 of the supporting base 12, the first inlet 14A has itsopening oriented in the width direction of the vehicle body and thesecond inlet 14B has its opening oriented in the front/rear direction ofthe vehicle body. Therefore, for example, by connecting a second supplypiping 48 to the second inlet 14B, the second supply piping 48 isarranged along the vehicle body frame 80 and the piping can thus berouted in a neatly arranged manner without the second supply piping 48projecting greatly in the vehicle width direction. Also, even in thiscase, by connecting the first supply piping 47 to the first inlet 14A,for example, piping connection that circumvents equipment (notillustrated) located adjacent to the air dryer 10 can be performedeasily.

Also, if the air dryer 10 cannot be mounted directly on the vehicle bodyframe 80, a bracket 81 extending in the vehicle width direction from thevehicle body frame 80 may be provided as indicated by broken lines inFIG. 6A and the air dryer 10 may be mounted on the bracket 81 using theright side surface 123 of the supporting base 12. In this case, thecollar members 32A are preferably located between the second mountingportions 32 provided on the right side surface 123 and the bracket 81.With this configuration, the air dryer 10 is mounted in the sameattitude as in the case of mounting on the vehicle body frame 80 usingthe rear surface 122 of the supporting base 12.

On the other hand, if the air dryer 10 is to be mounted on the vehiclebody frame 80 using the right side surface 123 of the supporting base12, a stay 80A is fixed to the vehicle body frame 80 as shown in FIG. 6Band mounting on the stay 80A is performed via the second mountingportions 32 provided on the right side surface 123 of the supportingbase 12. Similarly in this case, the collar members 32A are preferablylocated between the second mounting portions 32 provided on the rightside surface 123 and the bracket 81. The supporting base 12 of the airdryer 10 may be mounted directly on the vehicle body frame 80.

In the present mode, the first inlet 14A has its opening oriented in thefront/rear direction of the vehicle body. The second inlet 14B has itsopening oriented in the width direction of the vehicle body. Therefore,for example, by connecting the first supply piping 47 to the first inlet14A, the first supply piping 47 is arranged along the vehicle body frame80 and the piping can thus be routed in a neatly arranged manner withoutthe first supply piping 47 projecting greatly in the vehicle widthdirection. Also, even in this case, by connecting the second supplypiping 48 to the second inlet 14B, for example, piping connection thatcircumvents equipment (not illustrated) located adjacent to the airdryer 10 can be performed easily.

Also, if the air dryer 10 cannot be mounted directly on the vehicle bodyframe 80 and the stay 80A, a bracket 82 extending in the vehicle widthdirection from the vehicle body frame 80 may be provided as indicated bybroken lines in FIG. 6B and the air dryer 10 may be mounted on thebracket 82 using the rear surface 122 of the supporting base 12. Withthis configuration, the air dryer 10 is mounted in the same attitude asin the case of mounting on the vehicle body frame 80 using the rightside surface 123 of the supporting base 12.

As described above, the present embodiment includes the supporting base12, the drying agent container 50, and the outer cover 70. Thesupporting base 12 includes the inlet 14 receiving the compressed air tobe subject to the drying process and the outlet 16, which delivers theprocessed compressed air that has been subject to the drying process.The drying agent container 50 is supported on the supporting base 12,contains the drying agent 58 in the interior, and enables the dryingprocess to be performed by passage of the compressed air from the inlet14 through the drying agent 58. The outer cover 70, surrounds, on thesupporting base 12, the outer side of the drying agent container 50 anddefines the chamber 75 for storing the compressed air between itself andthe drying agent container 50. The supporting base 12 includes the rearsurface 122 as the first mounting surface and the right side surface 123as the second mounting surface, which are oriented in differentdirections and respectively have the first mounting portions 31 and thesecond mounting portions 32 formed thereon. The supporting base 12 alsoincludes the first inlet 14A and the second inlet 14B, which areoriented in different directions and receive the compressed air. Byselecting, in the process of mounting the supporting base 12 on thevehicle body frame 80 that is the mounting target, one of either therear surface 122 or the right side surface 123 and one of either thefirst inlet 14A or the second inlet 14B, the variation of combinationsof the mounting surface and the inlet is increased and mounting of theair dryer 10 on diverse mounting positions can be performed easily withthe same configuration. Also, improvement of the versatility andproductivity of the air dryer 10 is achieved because the air dryer 10 ofthe same configuration is mounted on diverse mounting positions.

Also, with the present embodiment, the first and second mountingsurfaces are formed on the mutually adjacent rear surface 122 and rightside surface 123 among the side surfaces of the supporting base 12 andtherefore the supporting base 12 can be easily changed in position withrespect to and mounted on the mounting target. Also, the first inlet 14Aand the second inlet 14B are collectively located at the corner portion,at which the front surface 120 and the left side surface 121 of thesupporting base 12 intersect and which is positioned away from the rearsurface 122 and the right side surface 123, and therefore in connectingthe supply piping to either the first inlet 14A or the second inlet 14B,the piping connecting process can be performed readily withoutinterference of the supply piping and the vehicle body frame 80 on whichthe rear surface 122 or the right side surface 123 is mounted.

Also, with the present embodiment, the first outlet 16A is located onthe front surface 120 of the supporting base 12, which faces the rearsurface 122 of the supporting base 12, and therefore a process ofmounting equipment, such as the protection valve 5, and the like, on thefirst outlet 16A can be performed easily.

Although the best embodiment for carrying out the present invention hasbeen described above, the present invention is not restricted to thedescribed embodiment and various modifications and changes are possiblebased on the technical idea of the present invention. For example,although in the present embodiment, between the first inlet 14A and thesecond inlet 14B, a sealing stopper (non-illustrated) is located at theinlet that is not used, the present invention is not restricted thereto.For example, a plurality of planned opening portions corresponding to aplurality of inlets may be provided in a manufacturing stage and a holemay be bored in any of the planned opening portions to form an inlet inaccordance with the mounting conditions of the supporting base 12.

With this configuration, a hole is bored in the planned opening portionfor the inlet that is known in advance to be actually used and workingprocesses are reduced and workability is improved correspondingly.Further, with this configuration, a hole is not bored in the plannedopening portion for an inlet that is not used and the process of closingoff this inlet with a sealing stopper, and the like, is made unnecessaryand air leakage from the inlet is prevented reliably.

Also, although the present embodiment is arranged with the flange 161being formed at the periphery of the first outlet 16A provided on thefront surface 120 of the supporting base 12, the protection valve 5being mounted on the flange 161, and the wet tank 46 being connected tothe second outlet 16B provided on the right side surface 123 of thesupporting base 12, the present invention is not restricted thereto, andthe wet tank 46 or the protection valve 5 may be made selectivelymountable on the first outlet 16A. If the wet tank 46 is to be mountedon the first outlet 16A, the protection valve 5 may be mounted in seriesto the wet tank 46. With this configuration, the equipment mounted onthe first outlet 16A can be selected in accordance with the mountingconditions of the supporting base 12 and the arrangement of peripheralequipment and diverse air circuit layouts is realized.

An embodiment of the present invention for achieving the second objectwill now be described based on drawings. The embodiment described belowis merely an embodiment and the embodiment will be described on thepremise that it is not restrictive of the present invention.

FIG. 7 is a cross-sectional view of a portion of an air dryer 201according to the present invention and a silencer 230 according to thepresent invention, FIG. 8(A) is a perspective view of the silencer 230as viewed from below, FIG. 8(B) is a perspective view of a state where alid member 240 forming the silencer 230 is opened, and FIG. 9 is a planview of the silencer 230 in the state where the lid member 240 isopened. In the drawings, lines are omitted as necessary to prevent thedrawings from becoming complicated.

The air dryer 201 includes a drying portion 203 at an upper portion of abase member 202 (for example, a metal molded part made of aluminum or analloy, and the like) that is to be a base. Compressed air dischargedfrom a non-illustrated air compressor is taken into the interior of theair dryer 201 from a first air intake port 204 (FIG. 8(A)) formed in thebase member 202. In addition to the first air intake port 204, thecompressed air discharged from the non-illustrated compressor is alsotaken in from a second air intake port 205 and is guided to an exhaustvalve 209 to be described below.

The compressed air taken into the interior of the air dryer 201, andmoisture and oil are removed from the air in the drying portion 203 Theair is then output from an output port 207 (FIG. 8A), stored in anon-illustrated external air tank, and used as necessary for driving anair driven device, such as an air brake, and the like The configurationof the drying portion 203 is the same as that of a publicly knownconfiguration and therefore illustration and description of the detailedconfiguration of the interior thereof will be omitted.

Some of the compressed air, from which moisture and oil have beenremoved in the air dryer 201, is also supplied to a pressure governor(non-illustrated) built into the air dryer 201. The non-illustratedpressure governor outputs a control command pressure for opening theexhaust valve 209, which is located at a lower portion of the air dryer201, to a control chamber 206 when the compressed air supplied from thecompressor to the air dryer 201 reaches a predetermined upper limitpressure.

When the exhaust valve 209 is opened, the air inside the drying portion203 is discharged to the exterior from a final discharge outlet(micropores 241) via an expansion chamber 232 and a noise absorbingmaterial housing chamber 236 to be described below. The exhaust in thisprocess is rapid and the rapid exhaust cleans an oil filter(non-illustrated) inside the drying portion 203 and also dischargesdrain, which contains moisture, oil, and the like, and has accumulatedin an upper portion of a valve element 212 of the exhaust valve 209, tothe exterior.

Also, the dry-processed air inside the drying portion 203 flows inreverse through a drying process passage (non-illustrated) inside thedrying portion 203 to be discharged to the exterior while taking upmoisture from a drying agent (non-illustrated) inside the drying portion203 and regeneration of the drying agent is thereby achieved. When thecontrol pressure from the pressure governor decreases and the exhaustvalve 209 closes due to a decrease of the pressure inside the controlchamber 206, the interior of the drying portion 203 returns to thecompressed air drying process state.

The exhaust valve 209 and a configuration (a principal portion of thepresent invention) at the downstream side of an exhaust flow passagewith respect to the exhaust valve 209 will now be described. The exhaustvalve 209 includes a valve body formed by integrally mold-forming apiston 210 formed of a metal material and a valve element 212 formed ofan elastic material. Reference numeral 211 denotes an O-ring forsealing.

Also, reference numeral 217 denotes a valve seat, and the opening andclosing of the exhaust valve 209 are performed by switching between astate where the valve element 212 is pressure-contacted against thevalve seat 217 and a state where the valve element 212 is separated fromthe valve seat 217 by vertical movement of the piston 210.

Reference numeral 15 denotes a return spring that urges the valve body,which is formed by the piston 210 and the valve element 212, in aclosing direction and the valve body is thereby maintained in a closedvalve state when the air compressor is in the loaded state. Referencenumeral 220 denotes a seat for the return spring 15 and referencenumeral 19 denotes C-ring for fixing the seat 220.

Until the dry air stored in the non-illustrated air tank reaches apredetermined pressure, that is, until the control command pressure(pressure inside the control chamber 206) from the non-illustratedpressure governor reaches the predetermined pressure, the exhaust valve209 must be maintained in the valve closed state. Also, when the controlcommand pressure (pressure inside the control chamber 206) from thenon-illustrated pressure governor reaches the predetermined pressure,the exhaust valve 209 must be put in the valve open state without fail.

The pressure receiving area of the exhaust valve 209 for receiving thecontrol pressure from the pressure governor (pressure inside the controlchamber 206), the pressure receiving area of the exhaust valve 209 forreceiving the pressure of the compressed air taken in from the secondair intake port 205, and the urging force of the return spring 15, whichurges the piston 210, are designed based on the above standpoints.

Next, a primary discharge outlet for exhaust air from the exhaust valve209 is formed by slits 225A to 225C formed in a cylindrical body 224.That is, the cylindrical body 224 is formed integral to the base member202, the plurality of slits (225A to 225C) extending in the cylindricalaxis direction (vertical direction in FIG. 7) are formed atpredetermined intervals in the circumferential direction, and drain andair are discharged from the slits 225A to 225C.

The cylindrical body 224 is configured such that its periphery issurrounded by a silencer case portion 231, which forms the silencer 230,and the inner side of the silencer case portion 231 is defined as theexpansion chamber 232. That is, the expansion chamber 232 is in a stateof being connected to the primary discharge outlet that discharges theair (and the drain) from the exhaust valve 209.

In the present embodiment, the silencer case portion 231, which definesthe expansion chamber 232, is also formed integral to the base member202 as is the cylindrical body 224, and the silencer case portion 231(the expansion chamber 232 and the noise absorbing material housingchamber 236 to be described below) is formed to have a rectangularshape.

By the configuration described above, the exhaust air discharged fromthe slits 225A to 225C is made to enter the expansion chamber 232 and isparticularly made to hit inner walls 233A to 233C of the expansionchamber 232 (the flow of the exhaust air at this point is indicated byarrows a, b, and c in FIG. 9).

The slits 225A to 225C respectively face the inner walls 233A to 233C ofthe expansion chamber 232, and the air discharged from the respectiveslits 225A to 225C is made to hit different inner walls 233A to 233Cinside the expansion chamber 232.

That is, the discharged air from the exhaust valve 209 is branched intoa plurality of flow passages and hits the inner walls inside theexpansion chamber 232 under respectively different conditions, therebyenabling the “noise range” in the process of discharge of air from theplurality of slits 225A to 225C to be dispersed, and a better silencingeffect can thereby be obtained.

By arranging so that at least either the angles or the distances bywhich the air discharged from the plurality of slits 225A to 225C hitsthe different inner walls 233A to 233C inside the expansion chamber 232differ, an even better silencing effect is obtained. Also, therespective slits 225A to 225C may be formed to differ in slit width.

However, there is an adverse effect on air discharge if the total airdischarging ability of the slits 225A to 225C is lower than the abilityto discharge air from the exhaust valve 209, and it is thus preferableto set the number and opening sizes of the slits at least so as not tohinder the ability to discharge air from the exhaust valve 209.

Although three slits (slits 225A to 225C) are formed in the presentembodiment, the number of slits is obviously not restricted thereto.Also, the respective positions at which the slits are formed as shown inFIG. 9 are obviously an example and the positions are not restrictedthereto. Also, although the inner walls 233A to 233C are configured tobe in one-to-one correspondence with the respective slits 225A to 225Cin the present embodiment, the configuration is not restricted theretoand, for example, a single inner wall may be configured to correspond toa plurality of slits.

Next, the noise absorbing material housing chamber 236 is connected tothe expansion chamber 232. As with the expansion chamber 232, the noiseabsorbing material housing chamber 236 is defined by the silencer caseportion 231 and the exhaust air is configured to pass through slits 34formed between the expansion chamber 232 and the noise absorbingmaterial housing chamber 236 (the flow of the exhaust air in thisprocess is indicated by arrows d in FIG. 9).

A noise absorbing material 237 (illustrated by hatching in FIG. 7 andomitted from illustration in FIGS. 8 and 9 for simplification of thedrawings) is provided in the noise absorbing material housing chamber236 and further reduction of the air exhaust noise is achieved by thenoise absorbing material 237.

Any of various materials may be used as such a noise absorbing material237 and in the present embodiment, a porous material, such as a sponge,and the like, is used. By using a porous material, such as a sponge, andthe like, an even better silencing effect is obtained by the dischargedair passing through numerous pores. However, this is just one exampleand any of other various noise absorbing materials may be used and, forexample, crushed aluminum, and the like, may be used.

Next, the expansion chamber 232 and the noise absorbing material housingchamber 236 are formed to a closed space by the lid member 240, and thenumerous micropores 241 forming the final discharge outlet fordischarging the drain and air to the exterior are formed so thatopenings thereof are directed vertically downward at positions of thelid member 240 corresponding to the noise absorbing material housingchamber 236.

Since all the numerous micropores 241 for discharging air to theexterior in the final stage are formed to open only vertically downwardin the present embodiment, the air discharge noise is emitted downwardand the air discharge noise can thereby be made difficult to hear.Reference numeral 242 denotes bolts for fixing the lid member 240 to thebase member 202 and reference numeral 243 denotes bolt holes therefore.

As described above, with the silencer 230 according to the presentembodiment, a high silencing effect is obtained by a synergistic effectof the air discharge noise attenuating effect due to the discharged airfrom the exhaust valve 209 hitting the inner walls 233A to 233C insidethe expansion chamber 232 and the noise absorbing effect due to thenoise absorbing material 37.

Also, with the present embodiment, the cylindrical body 224 forming theprimary discharge outlets (slits 225A to 225C), the expansion chamber232, and the noise absorbing material housing chamber 236 are formedintegrally on the base member 202 forming the base of the air dryer 201.Therefore cost reduction of the air dryer with silencer is achieved andthe volume occupied by the silencer 230 itself is reduced.

Also, by forming the components of the silencer 230 integrally on thebase member 202 forming the base of the air dryer 201, the strength isensured readily and an even better silencing effect is obtained bymaking the discharged air hit a rigid body. However, the presentinvention is not restricted to such an embodiment, and obviously, therespective components of the silencer 230 may be arranged as membersindependent of the base member 202, and the silencer 230 may beconfigured to be mounted on the base member 202 when being arranged asan independent body. In such cases, the slits 225A to 225C describedwith the present embodiment may also be formed not in the base member202 but at the silencer 230.

An embodiment of the present invention for achieving the third objectwill now be described based on drawings. The embodiment described belowis merely an embodiment and will be described on the premise that it isnot restrictive of the present invention.

FIGS. 10 and 11 are cross-sectional views of an exhaust valve 305according to the present invention, with FIG. 10 showing a valve closedstate and FIG. 11 showing a valve open state. In the drawings, lines areomitted as necessary to prevent the drawings from becoming complicated.Also, other configurations of the air dryer except the exhaust valve 305are the same as those of the air dryer according to the conventional artdescribed with reference to FIG. 12 and therefore illustration of suchcomponents will be omitted in FIGS. 10 and 11 and description thereofwill also be omitted below.

In FIGS. 10 and 11, reference numeral 303 denotes a control chamber towhich a control command pressure is output from a pressure governor(non-illustrated), reference numeral 305 denotes a pressure chamberreceiving the pressure of compressed air supplied from an air compressor(non-illustrated), and these respectively correspond to the controlchamber 355 and the pressure chamber 354 in the exhaust valve 356according to the conventional art described with reference to FIG. 12.

Reference numeral 302 denotes a base member (for example, a metal moldedpart made of aluminum or an alloy, and the like) that makes up a base ofthe air dryer, and an upper portion 307 a of a piston 307 to bedescribed below is inserted in a manner enabling sliding up and down inan opening 302 a formed in the base member 302. A projecting guideportion 302 b is formed on the base member 302, a guided hole 307 b isformed in an upper portion of the piston 307, and by the guide portion302 b entering the guided portion 307 b, the piston 307 is guided by theguide portion 302 b during vertical movements of the piston 307.

Also, with the present embodiment, a valve seat 312 is cited as acharacteristic point of the configuration formed in the base member 302.That is, the valve seat 312 is formed using a portion of the base member302, in other words, is formed integral to the base member 302.

Next, with the exhaust valve 305 according to the present invention, thepiston 307 and a valve element (seal) 309 are formed integrally by moldforming, and a valve body 306 is formed by the piston 307 and the valveelement 309. The valve element (seal) 309 is formed of an elasticmaterial and the piston 307 is formed of a metal material.

Unlike the exhaust valve 356 according to the conventional art shown inFIG. 12, the exhaust valve 305 according to the present invention isarranged so as to receive a pressing force in a valve opening directionby the air pressure received from the pressure chamber 304. Therefore inthe loaded state of the air compressor (non-illustrated), the exhaustvalve 305 is configured to be maintained in a valve closed state by theurging force of a return spring (which urges the piston 307 in the valveclosed state) as an urging means indicated by reference numeral 311.

When receiving the control command pressure from the pressure governor(non-illustrated), the pressure inside the control chamber 303 causesthe exhaust valve 305 to move downward against the urging force of thereturn spring 311 and the valve open state is attained where thecompressed air is discharged via a pathway indicated by arrows f in FIG.11. Reference numeral 316 denotes a cylindrical body formed integral tothe base member 302, reference numeral 315 denotes a seat of the returnspring, and reference numeral 314 denotes a C-ring fixing the seat 315.

Also, reference numeral 316 a denotes a slit formed in the cylindricalbody 16 and reference numeral 320 denotes an expansion chamber. The airdischarged via the exhaust valve 305 is guided via the slit 316 a andthe expansion chamber 320 to a noise absorbing material housing chamberindicated by reference numeral 321. The noise absorbing material housingchamber 321 is filled with a noise absorbing material, such as a porousmaterial, and the like, and the exhaust air is discharged to theexterior via the noise absorbing material and from a non-illustrateddischarge hole formed in a lid member 22.

The exhaust valve 305 must be maintained in the valve closed state untilthe control pressure (pressure inside the control chamber 3) from thenon-illustrated pressure governor reaches a predetermined pressure.Also, when the control pressure (pressure inside the control chamber 3)from the non-illustrated pressure governor reaches the predeterminedpressure, the valve open state must be attained without fail.

The pressure receiving area of the valve body 306 for receiving thecontrol pressure from the pressure governor (pressure inside the controlchamber 303), the pressure receiving area of the valve body 306 forreceiving the pressure of the compressed air in the pressure chamber304, and the urging force of the return spring 311 which urges the valvebody 306, are designed based on the above standpoints.

As described above, with the exhaust valve 305 according to the presentinvention, the valve body 306 has the structure of being pressed not inthe valve closing direction but in the valve opening direction by thepressure of the compressed air supplied from the air compressor. Thevalve closed state is maintained by the urging force of the returnspring 311 when the air compressor is in the loaded state so that thepiston 307 is not required to be formed to a T-like shape that is largein diameter at an upper portion from the standpoint of pressurereceiving area as in the exhaust valve according to the conventional artdescribed with reference to FIG. 12.

There is thus no need to ensure a large size for the opening 302 a forhousing the piston 307, and the large-diameter valve base (referencenumeral 364 in FIG. 12), which is conventionally required, is madeunnecessary. This contributes to cost reduction and enables improvementof the strength by lessening of pressure receiving members. The need toarrange the valve body 306 from several members due to reasons ofassembly is also eliminated and the valve body 306 can be formed by justthe piston 307 and the valve element 309 in the present embodiment,thereby enabling the structure of the exhaust valve to be simplified andcost reduction to be achieved as well.

In addition, with the present embodiment, the valve seat 312 is formedusing a portion of the base member 302 of the air dryer; that is, thevalve seat is formed integral to the base member 302 so that the exhaustvalve can be made even simpler in structure to achieve cost reduction.Although the valve seat 312 is formed using a portion of the base member302 in the present embodiment, it is not restricted thereto and may beprovided on another member.

Further in addition, the valve body 306 has the structure of beingpressed not in the valve closing direction but in the valve openingdirection by the pressure of the compressed air supplied from the aircompressor as described above. Also, the valve body 306 is configuredsuch that the valve closed state is maintained by the urging force ofthe return spring 311 when the air compressor is in the loaded state,and the valve is thus opened when the pressure of the compressed airbecomes an abnormal pressure when the air compressor is in the loadedstate. The exhaust valve 305 can thus be used as a safety valve.

An embodiment of the present invention for resolving the fourth problemwill now be described based on drawings.

FIG. 12 is a diagram of an example of a piping configuration of a truckor other vehicle that includes a valve device according to the presentembodiment. Principal portions of the configuration of the presentinvention are illustrated, and other members and flow passages for gasare omitted from illustration.

As shown in FIG. 12, an air processing system 501 provided in a brakesystem of the vehicle of the present embodiment includes a regenerationvalve device 510 (hereinafter referred to simply as “valve device”)having an air feeding time adjusting function and a drying portion 505.The piping configuration of the air processing system 501 of the presentembodiment may be used as an air brake system for a truck or othercommercial vehicle or as an air conditioning system for a generalautomobile.

Specifically, the air processing system 501 includes a compressor 502,which is a gas compressor, a gas tank 507 for the system, the valvedevice 510, the drying portion 505, an exhaust valve 503, which is a gasdischarging portion, and a silencer 504. Among these, the compressor 502is provided to compress a gas and deliver the compressed gas. Also, thegas tank 507 can store a dried gas and is configured to be used, forexample, in an air brake system, and the like. Yet further, the valvedevice 510 is put in a valve closed state when the pressure of the gasis not acting and is configured to be capable of being switched betweena valve open state and closed state by a pilot command.

Also, the drying portion 505 has a drying agent 506 in the interior andis provided to be capable of drying the gas that passes through. Yetfurther, the exhaust valve 503 is normally put in a valve closed stateand is configured to be capable of being switched between a valve openstate and closed state by a pilot command from a non-illustratedpressure governor. Also, the silencer 504 is provided to reduce thenoise generated when the gas is discharged.

One side of the valve device 510 with reference to the valve isconnected to the gas tank 507 by a first flow passage 530. The otherside is connected to the drying portion 505 by a second flow passage532. Further, the first flow passage 530 and the second flow passage 532are connected by a first check valve 508.

“Check valve” refers to a valve that is configured to be capable ofallowing a flow in one direction and stopping a flow in the oppositedirection.

In the present embodiment, the first check valve 508 is provided toallow the flow from the drying portion 505 to the gas tank 507 and stopthe flow from the gas tank 507 to the drying portion 505.

The first check valve 508 is a valve with a spring. When a pressure notless than a predetermined pressure acts, the gas flows from the dryingportion 505 to the gas tank 507 against the urging force of the spring.

Also, the compressor 502 and the exhaust valve 503 are connected to theside of the drying portion 505 opposite to the side connected to thevalve device 510. Yet further, the silencer 504 is connected to the sideof the exhaust valve 503 opposite to the side connected to the dryingportion 505 and the compressor 502.

The configuration and operation of the valve device 510 will now bedescribed in detail.

As will be described in detail below, the valve device 510 has a firsthole portion 516 used for air venting and filling and a second checkvalve 529 having a function of a check valve in a third flow passage 533parallel to the flow passage used for air venting and filling. In thepresent embodiment, a piston cup 521 (see FIG. 13 to FIG. 16)corresponds to the second check valve 529.

In a state where the exhaust valve 503 is closed, the compressed gasfrom the compressor 502 is delivered to the drying portion 505 and thecompressed gas is dried by the drying portion 505. The dried compressedgas is then delivered into the gas tank 507 via the first check valve508. In this process, the dried compressed gas also flows into the valvedevice 510 and switches the valve of the valve device 510 to the openstate. Specifically, the dried compressed gas flows from the second flowpassage 532 into a chamber of the valve device 510 main body via thesecond check valve 529 of the third flow passage 533 and the first holeportion 516. The valve of the valve device 510 is thereby switched tothe open state. The dried compressed gas is thus delivered into the gastank 507 via the valve device 510 as well.

With the present configuration, the gas flows into the chamber not onlyvia the first hole portion 516 but also via the second check valve 529of the third flow passage 533. Therefore in comparison to theabove-described configuration (see FIG. 17) in which the gas flows inonly via the hole portion 42 (see FIG. 17), the valve of the valvedevice 510 can be switched from the closed state to the open state at afaster timing. The requirement of rapid air filling can thus besatisfied.

Also, with the present configuration, the dry compressed gas is storedin the gas tank 507. When the pressure in the gas tank 507 reaches a setpressure, the non-illustrated pressure governor generates the controlpressure as an air pressure signal and switches the exhaust valve 503 tothe open state. The compressed gas from the compressor 502 is therebydischarged to the atmosphere from the exhaust valve 503 and the silencer504. Also, the dry compressed gas in the gas tank 507 flows through thevalve device 510 in reverse for just a predetermined time to regeneratethe drying agent 506 in the drying portion 505.

The valve device 510 is configured to activate the air feeding timeadjusting function in this process to cause the dry compressed air toflow in reverse for the predetermined time. As will be described indetail below, when the valve of the valve device 510 is put in the openstate and the dry compressed gas begins to flow in reverse, the gasflowing into the chamber is gradually vented from the first hole portion516 into the second flow passage 532. As the air feeding time adjustingfunction, the valve device 510 is configured to be switched to theclosed state when the predetermined time (for example, 30 seconds)elapses.

The gas used for regeneration is discharged to the atmosphere from theexhaust valve 503. Thereafter, when the value of the pressure in the gastank 507 falls below the set value due to use of the air brake, and thelike, the non-illustrated pressure governor switches the exhaust valve503 to the closed state. The dry compressed air is thereby delivered tothe gas tank 507 as described above and the pressure in the gas tank 507reaches the set pressure.

Details of the valve device 510 having the air feeding time adjustingfunction will now be described.

FIG. 13 is a schematic cross-sectional view of the valve deviceaccording to the present embodiment in the closed state.

As shown in FIG. 13, the valve device 510 of the present embodimentincludes a chamber 511, a piston 514, a valve element 528, and acompression coil spring 527 as an urging means 526.

Of the above, the chamber 511 is provided so that the pressure of gasacts thereon.

Also, the piston 514 is configured to be slidable in the interior of thechamber 511 in the axial direction of a shaft portion 515 of the piston514. Yet further, a first end (lower side in the drawing) in themovement direction of the piston 514 in the chamber 511 is connected tothe first flow passage 530. Further, the valve element 528 is located atthe first end of the piston 514. The valve element 528 is configured tomove integrally with the piston 514 and contacts a valve seat portion531 located at an opening portion of the first flow passage 530 toattain the valve closed state. Also, when the valve element 528separates from the valve seat portion 531, the valve is switched to theopen state.

Also, the compression coil spring 527 is located at the second end(upper side in the drawing) in the movement direction of the piston 514in the chamber 511. It is configured to urge the piston 514 toward thefirst end (lower side in the drawing).

Yet further, the piston 514 has the first hole portion 516 ofcomparatively small diameter formed therein. This is an orifice. Thefirst hole portion 516 is configured to make the gas flow from one sideto the other side in accordance with the difference between the pressureof the gas at the first end (lower side in the drawing) in the chamberwith reference to the piston 514 and the pressure of the gas at thesecond end (upper side in the drawing).

Specifically, if the pressure of the gas at the first end (lower side inthe drawing) is higher than the pressure at the second end (upper sidein the drawing), the gas flows from the first end (lower side in thedrawing) to the second end (upper side in the drawing). In contrast, ifthe pressure of the gas at the second end (upper side in the drawing) ishigher than the pressure at the first end (lower side in the drawing),the gas flows from the second end (upper side in the drawing) to thefirst end (lower side in the drawing). The length of time of the airfeeding time adjusting function is configured to be determined by theamount of gas flowing per unit time via the first hole portion 516 fromthe first end (lower side in the drawing) to the second end (upper sidein the drawing).

Also, the piston cup 521, which is formed of an elastic material, ismounted on the outer periphery of the piston 514. Specifically, a grooveportion 519 is formed in the outer periphery of the piston 514 and thepiston cup 521 is mounted so as to be fitted in the groove portion 519.The piston cup 521 can thus move integrally with the piston 514 in theaxial direction while contacting a first sliding surface 512 of thechamber 511.

The piston cup 521 is provided with a sealing portion 524, which sealsthe gas at one side of the chamber 511 with reference to the piston 514,between the piston 514 and the first sliding surface 512. The sealingportion 524 is formed so as to be bifurcated toward the space to besealed. In the present embodiment, the bifurcated portion will bereferred to as an “opening 525.” The piston cup 521 is mounted on thepiston 514 so that the opening 525 of the piston cup 521 faces the firstend (lower side in the drawing).

By the above, the gas is prevented from flowing out from the first end(lower side in the drawing) to the second end (upper side in thedrawing) and the gas can be made to flow from the second end (upper sidein the drawing) into the first end (lower side in the drawing) as willbe described in detail below. In other words, by making the opening 525face the first end (lower side in the drawing), the same effects asthose of a check valve is obtained.

Also, an O-ring 520 is mounted on the shaft portion 515 of the piston514. The O-ring 520 is provided so that the piston 514 and the shaftportion 515 move while it contacts a second sliding surface 513. Also, athrough-penetrating second hole portion 517 is formed in the interior ofthe shaft portion 515. The second end (upper side in the drawing) of thesecond hole portion 517 is configured such that the gas at the secondend (upper side in the drawing) of the chamber 511 can enter and exit.Yet further, the second end (upper side in the drawing) of the chamber511 is connected to the second flow passage 532.

When the compressed gas is not delivered from the compressor 502 and theair feeding time adjusting function is not operating, the valve device510 is put in the valve closed state by the compression coil spring 527.

The operation of the valve device 510 having the air feeding timeadjusting function will now be described.

FIG. 14 is a cross-sectional view illustrating the operation of thevalve device 510 when the inflow of gas is started.

As shown in FIG. 14, by the dry compressed gas being delivered from thecompressor 502, the dry compressed gas is delivered into the second end(upper side in the drawing) of the chamber 511 from the second flowpassage 532. The dry compressed gas delivered into the second end (upperside in the drawing) flows via the first hole portion 516 into the firstend (lower side in the drawing) of the chamber 511 with reference to thepiston 514.

The dry compressed gas delivered into the second end (upper side in thedrawing) of the chamber 511 flows into the first end (lower side in thedrawing) of the chamber 511 with reference to the piston 514 via aninterval between the piston cup 521 and the first sliding surface 512 ofthe chamber 511 as well. This is the third flow passage 533 describedabove. When the pressure of the dry compressed gas acts from the secondend (upper side in the drawing) toward the first end (lower side in thedrawing), it deforms the tip of the sealing portion 524 of the pistoncup 521, which is branched and bifurcated to spread, in a closingmanner. The above occurs because a suitable gap can thereby be formedbetween the piston cup 521 and the first sliding surface 512.

The gas can thus be accumulated in the first end (lower side in thedrawing) of the chamber 511 with reference to the piston 514 and raisethe pressure of the gas at the first end (lower side in the drawing) ina shorter time than the above-described configuration (see FIGS. 17(A)and 17(B)). The pressure of the gas at the first end (lower side in thedrawing) moves the piston 514 and the shaft portion 515 toward thesecond end (upper side in the drawing) against the urging force of thecompression coil spring 527. Consequently, the valve element 528 beginsto separate from the valve seat portion 531 and the valve is switchedfrom the closed state to the open state.

FIG. 15 is a schematic cross-sectional view of the valve device 510according to the present embodiment in the open state.

As shown in FIG. 15, the dry compressed gas delivered into the secondend (upper side in the drawing) of the chamber 511 flows, from the stateshown in FIG. 14, further into the first end (lower side in the drawing)of the chamber 511 with reference to the piston 514. The pressure of thegas at the first end (lower side in the drawing) is thereby increasedfurther. The piston 514 and the shaft portion 515 are thus moved furthertoward the second end (upper side in the drawing).

Consequently, the valve is completely opened.

Then, as mentioned above, the pressure in the gas tank 507 reaches theset pressure and the non-illustrated pressure governor switches theexhaust valve 503 to the open state. The compressed gas from thecompressor 502 is thereby discharged to the atmosphere from the exhaustvalve 503 and the pressure at the second end (upper side in the drawing)of the chamber 511 decreases. The dry compressed gas in the gas tank 507then flows into the interior of the chamber 511 via the first flowpassage 530. Specifically, the gas flows from the valve seat portion 531of the first flow passage 530, past the valve element 528 and the secondhole portion 17 of the shaft portion 515, and into the second end (upperside in the drawing) of the chamber 511 with reference to the piston514. The dry compressed gas then flows out from the second end (upperside in the drawing) of the chamber 511 to the second flow passage 532and is delivered to the drying portion 505 to be used to regenerate thedrying agent 506 in the drying portion 505. The gas used forregeneration is discharged to the atmosphere via the exhaust valve 503.

FIG. 16 is a cross-sectional view illustrating the operation of thevalve device 510 according to the present embodiment during operation ofthe air feeding time adjusting function.

As shown in FIG. 16, the air feeding time adjusting function by thefirst hole portion 516 begins to operate from the point at which thevalve of the valve device 510 is opened and the dry compressed gasbegins to flow in reverse. Specifically, the gas at the first end (lowerside in the drawing) of the chamber 511 with reference to the piston 514gradually flows out via the first hole portion 516 to the second end(upper side in the drawing). The amount of gas flowing out per unit timeis determined by the size of the first hole portion 516. The pressure ofthe gas at the first end (lower side in the drawing) of the chamber 511with reference to the piston 514 then gradually decreases.

During the gradual decrease, the dry compressed gas in the gas tank 507continues to flow through the first flow passage 530, the chamber 511,and the second flow passage 532 to the drying portion 505.

The pressure of the gas at the first end (lower side in the drawing) ofthe chamber 511 with reference to the piston 514 then graduallydecreases and the magnitude of the force by which the pressure of thegas pushes the piston 514 becomes smaller than the magnitude of theforce by which the compression coil spring 527 pushes the piston 514.The piston 514 and the shaft portion 515 are thus moved gradually towardthe first end (lower side in the drawing) by the urging force of thecompression coil spring 527.

Consequently, after elapse of the predetermined time (for example, 30seconds) from the point at which the valve is opened and the drycompressed air begins to flow in reverse, the valve element 528 contactsthe valve seat portion 531 and the valve is put in the closed state asshown in FIG. 13.

As described above, the valve device 510 is configured such that, as theair feeding time adjusting function, the dry compressed gas in the gastank 507 flows in reverse via the valve just for the predetermined time(for example, 30 seconds).

Although in the present embodiment, the piston cup 521 is mounted in thepredetermined direction on the piston 514 to make the amount of gasflowing per unit time into the valve device 510 from the second flowpassage 532 greater than that of the configuration described above (seeFIGS. 17(A) and 17(B)), the present invention is not restricted thereto.As far as the technical idea of the present invention is concerned, thevalve device 510 may have a configuration having the third flow passage533 and the second check valve 529 along the third flow passage 533apart from the piston cup 521. The piston cup 521 is used in the presentembodiment because the same actions and effects as the configurationhaving the third flow passage 533 and the second check valve 529 alongthe third flow passage 533 are obtained by simply changing the O-ring546 (see FIGS. 17(A) and 17(B)) of the above-described configuration tothe piston cup 521.

The regeneration valve device 510 for an air dryer according to thepresent embodiment is characterized by the chamber 511, the piston 514,the valve (528, 531), the urging means 526, the first hole portion 516,and the third flow passage 533. The chamber 511 is located between thedrying portion 505, which performs the drying process on the compressedgas supplied from the compressor 502, which is a gas compressor, and thegas tank 507, which stores the dry-processed dry compressed gas. Thepressure of the gas acts on the chamber 511. The piston 514 moves insidethe chamber 511 and defines the interior of the chamber 511 into thefirst end space (lower side in the drawing) at the gas tank 507 side andthe second end space (upper side in the drawing) at the drying portion505 side. The valve (528, 531) is put in the closed state by the piston514 moving toward the first end (lower side in the drawing) and put inthe open state by the piston 514 moving toward the second end (upperside in the drawing). The urging means 526 urges the piston 514 in thedirection in which the valve (528, 531) is closed. The first holeportion 516 is formed in the piston 514 and makes the gas flow from oneside to the other side in accordance with the difference between thepressure of the gas inside the first end space (lower side in thedrawing) and the pressure of the gas inside the second end space (upperside in the drawing). The third flow passage 533 is an auxiliary flowpassage having in it the second check valve 529 as a restricting means.The second check valve 529 allows the flow of gas in the direction fromthe second end space (upper side in the drawing) to the first end space(lower side in the drawing) of the chamber 511 and restricts the flow ofgas in the direction from the first end space (lower side in thedrawing) to the second end space (upper side in the drawing).

Also, the present embodiment is characterized by the followingconfiguration. That is, the third flow passage 533 is formed by theclearance between the outer peripheral surface of a flange portion ofthe piston 514 and the inner peripheral surface of the chamber 511. Therestricting means (corresponding to the second check valve 529) isformed by the piston cup 521 as a cup seal housed in the groove portion519 as a recessed portion, formed along the outer peripheral surface ofthe flange portion, in a manner such that the opening 525, which is anopening portion, faces the first end space (lower side in the drawing)and enlarging and reducing the opening 525 by elastic deformation. Whenflowing from the second end space (upper side in the drawing) in thechamber 511 into the first end space (lower side in the drawing) in thechamber 511, gas flows into the first end space (lower side in thedrawing) via the first hole portion 516 and additionally via the thirdflow passage 533 by the opening 525 of the piston cup 521 being reducedto open the clearance. When flowing out from the first end space (lowerside in the drawing) in the chamber 511 to the second end space (upperside in the drawing), gas flows out to the second end space (upper sidein the drawing) only via the first hole portion 516 by the opening 525of the piston cup 521 being enlarged to close the clearance.

Yet further, the present embodiment is characterized by the followingconfiguration. The gas is delivered from the drying portion 505 to thesecond end space (upper side in the drawing) in the chamber 511. The gasdelivered into the second end space (upper side in the drawing) flowsinto the first end space (lower side in the drawing) in the chamber 511,so that the pressure in the first end space (lower side in the drawing)of the chamber 511 increases. Accordingly, the piston 514 is moved bythe pressure to the second end (upper side in the drawing) against theurging force of the urging means 526 and the valve (528, 531) is put inthe open state by the movement of the piston 514. The gas in the firstend space (lower side in the drawing) in the chamber 511 flows out tothe second end space (upper side in the drawing) via the first holeportion 516. This lowers the pressure in the first end space (lower sidein the drawing) in the chamber 511. Then, the urging force of the urgingmeans 526 moves the piston 514 to the first end (lower side in thedrawing) and the valve (528, 531) is put in the closed state by themovement of the piston 514.

An air dryer according to the present embodiment is an air dryer thatincludes the drying portion 505 having the regenerable drying agent 506and the regeneration valve device 510 connected to a first end of theflow passage in the drying portion 505. The air dryer is characterizedby the following configuration. That is, the compressor 502 and theexhaust valve 503 as a gas discharge portion are connected to the secondend of the flow passage in the drying portion 505. The valve (528, 531)of the regeneration valve device 510 is put in the open state by the gasbeing delivered by the compressor 502 to the first end space (lower sidein the drawing) inside chamber 511 via the first hole portion 516 andthe third flow passage 533 of the regeneration valve device 510. By theexhaust valve 503 being put in the atmosphere released state, the drycompressed gas inside the gas tank 507 is delivered to the dryingportion 505 via the valve (528, 531) of the regeneration valve device510 and discharged from the exhaust valve 503.

The present invention is not restricted to the above-describedembodiment, various modifications are possible within the scope of theinvention described in the claims, and obviously such modifications areincluded within the scope of the present invention.

An embodiment of the present invention will now be described withreference to the drawings.

FIG. 18 is a diagram of a configuration of a compressed air supplysystem 601 according to an embodiment to which the present invention isapplied.

The compressed air supply system 601 (compressed air supply device for avehicle) shown in FIG. 18 is a device for supplying compressed air fordriving, for example, to a pneumatic brake device installed in a largevehicle, such as a truck or bus, and the like The system 601 is formedby a compressor 604 (air compressor), an ECU (regeneration controlmeans) 602 controlling the compressor 604, and an air dryer module 610,which removes the moisture in the compressed air discharged from thecompressor 604 and supplies the dried compressed air to a load (forexample, the brake device) of the vehicle.

The ECU 602 is communicably connected via a CAN (controller areanetwork) 603 to respective devices, such as an engine 605, a vehiclespeed detector (vehicle speed detecting means) 606, and the like, of thevehicle in which the compressed air supply system 601 is installed andacquires information on the vehicle and controls operations of therespective devices through the CAN 603. Specifically, informationrelated to traveling conditions of the vehicle, such as informationrelated to the vehicle speed of the vehicle, information related to thetraveling distance of the vehicle, and the like, and information relatedto operation conditions of an air dryer 632 to be described below areinput into the ECU 602. Based on the input information, the ECU 602controls the engine of the vehicle and controls the operations of thecompressor 604 and the air dryer module 610. Reference numeral 607 is aheater for heating to prevent freezing of moisture inside the air dryermodule 610 during cold months, and the like

The air dryer module 610 includes an output port 621 to which a load 651is connected, an output port 622 to which a load 652 is connected, anoutput port 623 to which a load 653 is connected, an output port 624 towhich a load 654 is connected, and an output port 625 to which a load655 is connected.

The loads 651 to 653 form the brake device. In the present embodiment,the load 651 is a main brake (service brake) for the front wheels, theload 652 is a main brake (service brake) for the rear wheels, and theload 653 is a parking brake. The loads 654 and 655 are accessories, suchas a horn, clutch driving mechanism, and the like, that are driven bythe compressed air.

Also, the loads 651 to 655 include compressed air circuits (servicebrake circuits, parking brake circuit) 651 a to 655 a, through which thecompressed air flows, and air tanks 651 b to 655 b are respectivelyconnected to the compressed air circuits 651 a to 655 b.

The air dryer module 610 includes a pressure controlling solenoid valve701 and a regeneration solenoid valve 702, which are opened and closedby control by the ECU 602, pressure sensors 721, 722, and 723, whichdetect air pressures at respective portions of the air dryer module 610and output the detection values to the ECU 602, and a humidity sensor724, which detects the relative humidity of the compressed air furtherdownstream than the air dryer 632 in the air dryer module 610 andoutputs the detection values to the ECU 602. The detection values of thehumidity sensor 724 include temperature information. The ECU 602 makesthe pressure controlling solenoid valve 701 and the regenerationsolenoid valve 702 open and close based on the detection values of thepressure sensors 721 to 723 and makes the regeneration solenoid valve702 open and close based on the detection values of the humidity sensor724.

The compressor 604 is coupled to the engine 605 via a non-illustratedauxiliary belt and compresses air using the driving force of the engine605. The pressure controlling solenoid valve 701 is connected via acontrol line 626 to the compressor 604. The pressure controllingsolenoid valve 701 switches the compressor 604 between a loaded state,in which the compressor 604 compresses air, and an unloaded state inwhich compression is not performed so that, for example, the detectionvalue of the pressure sensor 723 is within a predetermined pressurerange, and controls the operation of the compressor 604 by opening andclosing in accordance with the detection value of the pressure sensor723.

A discharge pipe (discharge line) 611 of the compressor 604 is connectedto an inflow pipe 631 of the air dryer module 610, and the air dryer 632is connected to the inflow pipe 631. The air dryer 632 houses a dryingagent inside a case and moisture and other foreign matter contained inthe compressed air discharged from the compressor 604 are removed by thedrying agent.

A branch pipe 631A branching from the inflow pipe 631 is connectedbetween the compressor 604 and the air dryer 632 and an exhaust valve633 and an exhaust outlet 634 are connected in series to the branch pipe631A. When the exhaust valve 633 opens, the compressed air in the mainbody of the air dryer 632 is discharged directly to the exterior fromthe exhaust outlet 634. The exhaust valve 633 is controlled by airpressure and a control line 639 thereof is connected to the regenerationsolenoid valve 702. The regeneration solenoid valve 702 is a solenoidvalve for controlling a drying agent regeneration operation of the airdryer 632, is opened and closed by control by the ECU 602, and appliesthe air pressure at the downstream side of the air dryer 632 to theexhaust valve 633 in the valve open state. The exhaust valve 633 isnormally closed and opens to release the compressed air from the exhaustoutlet 634 only when the air pressure from the regeneration solenoidvalve 702 is applied thereto.

When the exhaust valve 633 opens in a state where the air pressureinside the air dryer module 610 is sufficiently high, the compressed airstored at a further downstream side of the air dryer 632 (for example,in a supply passage 635 or the air tank 655 a) flows in reverse insidethe case of the air dryer 632 and is released from the exhaust outlet634. In this process, the air passing through the case becomes extremelydry due to the rapid pressure reduction and takes up the moisture fromthe drying agent inside the case and the drying agent is thusregenerated. After regeneration, the drying agent is recovered inadsorptive capacity for adsorbing moisture and is capable of removingthe moisture in the compressed air. The regeneration operation isexecuted by opening of the regeneration solenoid valve 702 by the ECU602 at a predetermined regeneration timing (predetermined timing), suchas at each preset time or when the air pressure inside the air dryermodule 610 meets a condition set in advance, and the like. In thepresent embodiment, the ECU 602, the regeneration solenoid valve 702,and the exhaust valve 633 function as a regeneration means.

Also, another branch pipe 631B, which branches from the inflow pipe 631,is connected between the compressor 604 and the air dryer 632, and thebranch pipe 631B is connected to a supply port 628 via a pneumaticpressure supply valve 636. The pneumatic pressure supply valve 636includes an operation switch 636A, which is operated on and offmanually. When the operation switch 636A is pressed, the pneumaticpressure supply valve 636 opens to release the compressed air from thesupply port 628. The supply port 628 is configured to be connectable,for example, to a valve (air supply port) of a tire of an automobile andair can be replenished to the tire by operation of the operation switch636A. Also, a safety valve 637 is provided in a branch pipe 635Abranched from the supply passage 635 at the downstream side of the airdryer 632. The safety valve 637 is a valve that is opened when the airpressure inside the supply passage 635 or in the air tanks 651 b to 655b rises abnormally to release the pressure to the exterior.

A branch chamber 638 is connected to the supply passage 635 furtherdownstream than the air dryer 632, and three supply passages 6640, 641,and 642 are connected to the branch chamber 638. A pressure reducingvalve 643 is provided in the supply passage 640 and at the downstreamside of the pressure reducing valve 643, the supply passage 640 branchesinto two supply passages 6640A and 640B, and the supply passages 6640Aand 640B are respectively connected to the output ports 621 and 622 viaservice brake pressure protection valves 644 and 645. Also, anothersupply passage 641 connected to the branch chamber 638 is provided witha pressure reducing valve 646 and a pressure protection valve 647 andbranches into two supply passages 641A and 641B at the downstream sideof the pressure protection valve 647. The supply passages 641A and 641Bare respectively connected to the output ports 623 and 624 via a parkingbrake pressure protection valve 648 and an accessory pressure protectionvalve 649. Further, the other supply passage 642 connected to the branchchamber 638 is connected to the output port 625.

In each of the service brake pressure protection valves 644 and 645, athrottle and a check valve are arranged in parallel. Each of the servicebrake pressure protection valves 644 and 645, the parking brake pressureprotection valve 648, and the accessory pressure protection valve 649closes when pressure loss occurs in the corresponding compressed aircircuit among the circuits 651 a to 654 a, through which compressed airflows, in the corresponding load among the loads 6651 to 654 connectedto the output ports 621 to 624, that is, when the air pressure in thecorresponding circuit falls below a predetermined valve closing pressurevalue. Also, each of the service brake pressure protection valves 644and 645, the parking brake pressure protection valve 648, and theaccessory pressure protection valve 649 is configured to open when theair pressure inside the supply passage in which the pressure protectionvalve is located exceeds a predetermined valve opening pressure value.

Also, a bleed-back passage 660 is located between the supply passage 642connected to the branch chamber 638 and a supply passage 641A at thedownstream side of the parking brake pressure protection valve 648. Thebleed-back passage 660 puts the respective supply passages 642 and 641Ain communication. The bleed-back passage 660 includes a check valve 661that prevents the flow of air from the supply passage 642 (that is, thebranch chamber 638) to the output port 623. The check valve 661 openswhen the air pressure inside the supply passage 641A falls below the airpressure inside the supply passage 642 and thereby functions to releasethe pressure inside the supply passage 641A (for example, the air tank653 b for the parking brake).

The pressure sensor 723 detects the air pressure in the supply passage635, the pressure sensor 721 detects the air pressure at the downstreamside of one service brake pressure protection valve 44, that is, the airpressure at the output port 621, and the pressure sensor 122 detects theair pressure at the output port 622 at the downstream side of the otherservice brake pressure protection valve 645. The detection values areoutput continually from the respective pressure sensors 721 to 723 tothe ECU 602. Also, the humidity sensor 724 detects the relative humidityin the supply passage 635 and its detection value is continually outputto the ECU 602.

With the parking brake device of the vehicle corresponding to the load653, the braking force is released by air pressure to enable travel.Specifically, the parking brake has a configuration where the brakingforce is exhibited by expansion of a brake shoe by the force of a springduring parking and, during release, the brake shoe is closed against theforce of the spring by the air pressure supplied from the air dryermodule 610.

Therefore when the air tank 653 b is sufficiently filled with compressedair, the parking brake device can release the parking brake by means ofthe air pressure. On the other hand, when pressure loss occurs at thecompressed air circuit 653 a corresponding to the parking brake, thesupply of compressed air to the compressed air circuit 653 a isinterrupted by closing of the parking brake pressure protection valve648 and the parking brake thus becomes unreleasable.

From the standpoint of safety, the parking brake device must be capableof being released when the main brake devices are usable, and it ispreferable that the parking brake should not be released when the airpressures in the air tanks 651 b and 652 b corresponding to the mainbrake devices are insufficient.

Therefore, in an initial state (for example, when the pressures insidethe air tanks 651 b and 652 b are not sufficient in a new car state orduring a vehicle inspection, and the like), the supply of compressed airto the compressed air circuit 653 a corresponding to the parking brakemust be interrupted until the air pressures inside the air tanks 651 band 652 b become sufficient. In the present configuration, the pressureprotection valve 647 is located in the supply passage 641 connected tothe branch chamber 638 and the valve opening pressure setting of thepressure protection valve 647 is set higher than the valve openingpressure settings of the service brake pressure protection valves 645and 46 to enable prevention of the supplying of compressed air to theair tank 653 b of the parking brake device before the air pressuresinside the air tanks 651 b and 652 b of the main brake devices becomesufficient.

Further, in the present configuration, the bleed-back passage 660 isprovided to make the parking brake unreleasable when pressure lossoccurs at the compressed air circuits 651 a and 652 a corresponding tothe main brake devices. Specifically, when pressure loss occurs at thecompressed air circuits 651 a and 652 a, the air pressure inside thesupply passage 642 decreases, the check valve 661 of the bleed-backpassage 660 opens, and the air inside the air tank 653 b is releasedthrough the bleed-back passage 660. Further, in accompaniment with thedecrease of air pressure inside the air tank 653 b, the parking brakepressure protection valve 648 closes. The supply of compressed air tothe compressed air circuit 653 a is thereby interrupted and the parkingbrake is made unreleasable.

Also, the pressure protection valve 647 is configured to have the samestructure as service brake pressure protection valves 644 and 645, theparking brake pressure protection valve 648, and the accessory pressureprotection valve 649. The respective pressure protection valves can thusbe standardized so that standardization of parts is achieved and asolenoid valve controlled according to a pressure detected by a servicebrake circuit and a line for outputting a command pressure from thesolenoid valve as in a conventional control valve are made unnecessary,thereby enabling realization of simplification of the configuration.

As described above. the ECU 602 opens the regeneration solenoid valve702 at the predetermined regeneration timing to apply the control airpressure to the exhaust valve 633 via the regeneration solenoid valve702 and opens the exhaust valve 633 to perform regeneration of thedrying agent of the air dryer 632. In the process of regenerating thedrying agent, drain water that contains oil is discharged through theexhaust valve 633, and therefore at a location where the discharge ofdrain water is undesirable in terms of sanitation management, such as inpremises of a food factory or a precision parts factory, it ispreferable to avoid performing the regeneration of the drying agent.

Normally, in factory premises, the traveling speed of a vehicle isrestricted to a low speed. Therefore with the present embodiment, theECU 602 acquires the vehicle speed information detected by the vehiclespeed detector 606 through the CAN 603, compares the vehicle speedinformation with a predetermined reference speed (for example, 20 km/h).If a state where the vehicle speed is slower than the reference speed issustained for a predetermined time, the ECU 602 assumes that the vehicleis travelling within factory premises or is stopped within factorypremises and inhibits the regeneration operation while this state issustained. In the present embodiment, the ECU 602 functions as aregeneration inhibiting control means. Also, the reference speed and thepredetermined time are stored in a non-illustrated nonvolatile storagemeans (for example, an EEPROM), which is configured to enable rewritingaccording to vehicle model, and the like

On the other hand, if regeneration is inhibited over a long period oftime, the adsorptive capacity of the drying agent of the air dryer 632decrease gradually, and therefore the relative humidity of thecompressed air inside the supply passage 635 and the air tanks 651 b to655 b increase. This causes adverse effects (for example, inoperabilitydue to promotion of corrosion or freezing of the drain, and the like) onequipment further downstream of the air dryer 632. Therefore, even inthe state where the regeneration operation is inhibited, if thedetection value of the humidity sensor 724 exceeds a reference value atwhich dew condensation may occur inside the supply passage 635 or theair tanks 651 b to 655 b, the ECU 602 opens the regeneration solenoidvalve 702 and forcibly executes the drying agent regeneration operation.In this case, the ECU 602 functions as a forcible regeneration means.

Also, even during travel outside factory premises, a situation can occurin which the vehicle speed remains slower than the reference speed forthe predetermined time due to a road traffic jam, and the like. In thiscase, if the regeneration of the drying agent is inhibited uniformlyunder the condition that the vehicle speed is slower than the referencespeed, the adsorptive capacity of the drying agent will decrease.Therefore with the present embodiment, a configuration is possible wherea switch 608 that is manually operable by a driver is connected to theECU 602 and the ECU 602 inhibits the regeneration of the drying agent ifthe switch 608 is in the on state and the state in which the vehiclespeed is slower than the reference speed is sustained for thepredetermined time. The switch 608 is located close to the driver seatand an appropriate regeneration operation can be performed by operatingthe switch in accordance with road conditions.

Also, besides the switch 608, whether or not the regeneration is to beinhibited may be determined from the position information of the vehicleitself and the vehicle speed information. For example, a configurationis possible where factory premises or other regeneration inhibited areais set in advance in the map information of a navigation device(non-illustrated) connected to the CAN 603 and the ECU 602 inhibits theregeneration of the drying agent if the position of the vehicle itselfthat is acquired by a GPS (global positioning system) of the navigationdevice, and the like, is within the regeneration inhibited area and thestate in which the vehicle speed is slower than the reference speed issustained for the predetermined time. In this case, a regenerationinhibited area is set by designating a plurality of coordinates thatindicate a boundary of the area on the map information and is set as thearea surrounded by the respective coordinates. If the precision of theposition information of the vehicle itself that is acquired by a GPS,and the like, improves, it is also possible to determine being in oroutside a regeneration inhibited area from the position information ofthe vehicle itself alone to restrict the regeneration of the dryingagent.

The drying agent regeneration process by the ECU 602 will now bedescribed with reference to FIG. 19.

First, the ECU 602 determines whether or not the compressor 604 is inthe unloaded state (step S1). This is because if the drying agentregeneration is performed with the compressor 604 being in the loadedstate, the compressed air amount may be insufficient. If the compressor604 is determined not to be in the unloaded state here (step S1: No),the process is ended, while if it is determined to be in the unloadedstate (step S1: Yes), the ECU 602 determines whether or not aregeneration timing that has been set in advance has arrived (step S2).

If it is determined that it is presently not the regeneration timing(step S2: No), the process is ended, while if it is presently theregeneration timing (step S2: Yes), the ECU 602 determines whether ornot the vehicle speed detected by the vehicle speed detector 606 isslower than the predetermined reference speed (for example, 20 km/h)(step S3). To avoid chattering in the process of making thisdetermination, it is preferable for the ECU 602 to determine that thevehicle speed is slower than the reference speed if the state where thevehicle speed is slower than the reference speed is sustained for apredetermined time. It is also preferable for the vehicle speed to bedetermined to be faster than the reference speed if the state where thevehicle speed is faster than the reference speed is sustained for apredetermined time.

If the vehicle speed is determined to be faster than the reference speedhere (step S3: No), the process is ended, while if the vehicle speed isdetermined to be slower than the reference speed (step S3: Yes), the ECU602 determines whether or not the switch 608 is on (step S4). The switch608 is a switch for selecting whether or not to inhibit the regenerationprocess based on the vehicle speed. For example, if the vehicle speed isslow simply because of a road traffic jam, the regeneration process isnot inhibited accordingly and the normal regeneration process isexecuted.

If the switch 608 is determined not to be on here (step S4: No), the ECU602 performs the normal drying agent regeneration process in accordancewith the regeneration timing (step S5). Control of the regenerationprocess in consideration of the traveling state can thereby be executed.

Also, if the switch 608 is on (step S4: Yes), the ECU 602 inhibits thedrying agent regeneration process regardless of the regeneration timing(step S6). By this configuration, the timing of the drying agentregeneration operation can be controlled easily based on the vehiclespeed, and the regeneration operation is suppressed at locations, forexample, within factory premises, where the traveling speed isrestricted and the discharge of drain water is undesirable.

Thereafter, the ECU 602 determines whether or not the humidity leveldetected by the humidity sensor 724 is not less than a threshold levelset in advance (step S7). The threshold level is set in advance to ahumidity level at which the possibility of dew formation inside thesupply passage 635 or any of the air tanks 651 b to 655 b is high and ahigh humidity abnormality will occur if driving is sustained as it is.

If it is determined that the humidity level of the compressed air isless than the predetermined threshold level (step S7: No), the processis ended, while if it is determined that it is not less than thehumidity level of the compressed air (step S7: yes), the ECU 602 outputsa valve opening signal to the regeneration solenoid valve 702 to openthe exhaust valve 633 and forcibly execute drying agent regenerationprocess (step S8) and then ends the process. The compressed air of highhumidity inside the supply passage 635 or any of the air tanks 651 b to655 b is thereby discharged and the compressed air from which moistureis removed through the regenerated drying agent flows into the supplypassage 635 to enable the respective equipment downstream of the airdryer 632 to operate normally.

As described above, the present embodiment, the compressed air supplysystem 601 includes the compressor 604 installed in the vehicle and theair dryer 632 removing moisture and other foreign matter contained inthe compressed air discharged from the compressor 604. The system 601supplies the compressed air that has passed through the air dryer 632 tothe brake device of the vehicle. The system 601 includes theregenerating means regenerating the drying agent in the air dryer 632 atthe predetermined timing and the vehicle speed detector 606 detectingthe vehicle speed of the vehicle. The ECU 602 inhibits the regenerationof the drying agent regardless of the predetermined timing if thedetected vehicle speed is slower than a predetermined reference speed.The timing of the drying agent regeneration operation can thus becontrolled easily based on the vehicle speed and the regenerationoperation is suppressed at locations, for example, within factorypremises, where the traveling speed is restricted and the discharge ofdrain water is undesirable.

Also, the regenerating means includes the exhaust valve 633 located inthe air dryer 632 and the regeneration solenoid valve 702 applying theair pressure for control to the exhaust valve 633 via the control line626. The ECU 602 opens the regeneration solenoid valve 702 at thepredetermined timing to apply the air pressure to the exhaust valve 633to open the exhaust valve 633 and performs regeneration control of thedrying agent in the air dryer 632. Therefore in comparison to theconventional configuration where regeneration is performed whenreceiving an air pressure signal from a pressure governor, the controlof whether or not to regenerate the drying agent can be performedreadily and the timing of the drying agent regeneration operation can becontrolled easily.

Also, with the present embodiment, the humidity sensor 724 is locateddownstream of the drying agent and if the humidity level detected by thehumidity sensor 724 indicates a humidity level not less than thethreshold set in advance, the ECU 602 forcibly executes the drying agentregeneration even if the drying agent regeneration is inhibited so thatthe compressed air of high humidity inside the supply passage 635 or anyof the air tanks 651 b to 655 b is thereby discharged and the compressedair from which moisture is removed through the regenerated drying agentflows into the supply passage 635 to resolve a state where a humiditylevel becomes no less than the threshold set in advance and enable therespective equipment downstream of the air dryer 632 to operatenormally.

The above-described embodiment illustrates an embodiment to which thepresent invention is applied and the present invention is not restrictedto the above embodiment. For example, although the embodiment isconfigured such that if the humidity level indicates a humidity levelnot less than the threshold set in advance, the ECU 602 forciblyexecutes the drying agent regeneration even if the drying agentregeneration is inhibited, the present invention is not restrictedthereto. For example, a configuration is also possible where, if thedrying agent regeneration is inhibited, the ECU 602 puts theregeneration operation on standby until the inhibition is canceled (thevehicle speed becomes not less than the reference value, the switch 608is turned on, or the position information of the vehicle itself fallsoutside the regeneration inhibited area) and forcibly performs theregeneration regardless of the regeneration timing when the inhibitionis canceled. With this configuration, the discharge of drain waterwithin factory premises is prevented because the regeneration operationis suppressed within factory premises or other regeneration inhibitedarea, and the state in which the relative humidity of the compressed airin the supply passage 635 and the air tanks 651 b to 655 b is raised isavoided from being sustained for a long period of time and adverseeffects on equipment downstream of the air dryer 632 is reduced becauseonce the inhibition is cancelled, the regeneration is performed forciblyregardless of the regeneration timing.

Also, the vehicle to which the compressed air supply device for avehicle according to the present invention is applicable is notrestricted in particular and may be any of large vehicles, smallvehicles, special vehicles, trailers, two-wheeled vehicles, andthree-wheeled vehicles and the scale and form thereof are arbitrary.

An embodiment of the present invention will now be described based ondrawings.

FIG. 19 is a schematic view of a piping of an air processing system 801that includes a valve device 810 according to the present embodiment.Principal portions of the configuration of the present invention areillustrated and other members and flow passages for gas are omitted fromillustration.

As shown in FIG. 19, the air processing system 801 of the presentembodiment includes the valve device 810 having an air feeding timeadjusting function. As an example, this will be described as the valvedevice 810 for regeneration of an air dryer (805).

The air processing system 801 of the present invention includes thevalve device 810 and the drying portion 805.

The piping configuration of the air processing system 801 of the presentembodiment may be used as an air brake system for a truck or othercommercial vehicle or as an air conditioning system for a generalautomobile.

Specifically, the air processing system 801 includes a compressor 802,which is a gas compressor, a gas tank 807 for the system, the valvedevice 810, the drying portion 805, an exhaust valve 803, which is a gasdischarging portion, and a silencer 804.

Among these, the compressor 802 is provided to compress a gas and feedthe compressed gas. Also, the gas tank 807 can store a dried gas and isconfigured to be used, for example, in an air brake system, and thelike. Yet further, the valve device 810 is put in a state where a firstvalve 822 (see FIG. 20 to FIG. 23) to be described in detail below isclosed when the pressure of the gas is not acting and is configured tobe capable of switching the first valve 822 between a valve open stateand closed state by a pilot command.

Also, the drying portion 805 has a drying agent 806 in the interior andis provided to be capable of drying the gas that passes through. Yetfurther, the exhaust valve 803 is normally put in a valve closed stateand is configured to be capable of being switched between a valve openstate and closed state by a pilot command from a non-illustratedpressure governor. Also, the silencer 804 is provided to reduce thenoise generated when the gas is discharged.

One side of the valve device 810 with reference to the first valve 822is connected to the drying portion 805 by a first flow passage 814. Theother side is connected to the gas tank 807 by a second flow passage815. Further, the first flow passage 814 and the second flow passage 815are connected by a check valve 808.

“Check valve” refers to a valve that is configured to be capable ofallowing a flow in one direction and stopping a flow in the oppositedirection.

In the present embodiment, the check valve 808 is provided to allow theflow from the drying portion 805 to the gas tank 807 and stop the flowfrom the gas tank 807 to the drying portion 805.

Also, the compressor 802 and the exhaust valve 803 are connected to theside of the drying portion 805 opposite to the side connected to thevalve device 810. Yet further, the silencer 804 is connected to the sideof the exhaust valve 803 opposite to the side connected to the dryingportion 805 and the compressor 802.

The configuration and operation of the valve device 810 in the airprocessing system 801 will now be described briefly.

As will be described in detail below, the valve device 810 is connectedto a throttle valve 812 and an atmosphere exhaust outlet 813 used forair venting.

In a state where the exhaust valve 803 is closed, the compressed gasfrom the compressor 802 is delivered to the drying portion 805 and thecompressed gas is dried by the drying portion 805. The dried compressedgas is then delivered into the gas tank 807 via the first check valve808.

In this process, the dried compressed gas also flows into the valvedevice 810 from the first flow passage 814. A second valve 825 (see FIG.20 to FIG. 23) is thereby opened by a second piston 824 (see FIG. 20 toFIG. 23). The compressed gas in the gas tank 807 thus flows into avolume chamber 811 from the second flow passage 815 and via the secondvalve 825.

The dried compressed gas delivered into the gas tank 507 is stored inthe gas tank 807. When the gas pressure in the gas tank 807 reaches aset predetermined value, the non-illustrated pressure governor generatesthe control pressure as an air pressure signal and switches the exhaustvalve 803 to the open state. The compressed gas from the compressor 802is thereby discharged to the atmosphere from the exhaust valve 803 andthe silencer 804. Also, the dry compressed gas in the gas tank 807 flowsvia the valve device 810 to the drying portion 805 for just apredetermined time to regenerate the drying agent 806.

The valve device 810 is configured to activate the air feeding timeadjusting function in this process, thereby making the dry compressedair flow to the drying portion 805 for just the predetermined time. Aswill be described in detail below, when the exhaust valve 803 isswitched to the open state, the first valve 822 of the valve device 810is put in the open state and the dry compressed gas begins to flow tothe drying portion 805. The gas flowing into the volume chamber 811 isthen gradually vented to the atmosphere via the throttle valve 812 andthe atmosphere exhaust outlet 813. As the air feeding time adjustingfunction, the first valve 822 of the valve device 810 is configured tobe switched to the closed state when the predetermined time (forexample, 30 seconds) elapses.

The gas used for regeneration is discharged to the atmosphere from theexhaust valve 803. Thereafter, when the value of the gas pressure in thegas tank 807 falls below the set value due to use of the air brake, andthe like, the non-illustrated pressure governor switches the exhaustvalve 803 to the closed state. The dry compressed air is therebydelivered to the gas tank 807 as described above and the gas pressure inthe gas tank 807 reaches the set gas pressure.

The piping connections of the valve device 810 in the air processingsystem 801 and the structure of the valve device 810 will now bedescribed.

FIG. 20 is a schematic cross-sectional view of the valve device 810according to the present embodiment.

As shown in FIG. 20, the valve device 810 has the volume chamber 811, ahole portion 828, a first cylinder portion 817, a first piston 818, asecond cylinder portion 823, a second piston 824, the first flow passage814, the second flow passage 815, and the third flow passage 816. Ofthese, the volume chamber 811 is provided to accumulate the compressedair as mentioned above. Also, the hole portion 828 is configured toenable the compressed gas in the volume chamber 811 to flow out from thevolume chamber 811.

Yet further, a first end of the first cylinder portion 817 is connectedto the volume chamber 811. The first piston 818 is provided to beslidable in the interior of the first cylinder portion 817. ThreeO-rings 821 are mounted as sealing members on the outer periphery of thefirst piston 818. The three O-rings 821 are configured to partition theinternal space of the first cylinder portion 817 into four compartmentsin the movement direction of the first piston 818. The compartments area first compartment A, a second compartment B, a third compartment C,and a fourth compartment D starting from the compartment at the firstend connected to the volume chamber 811.

The first piston 818 is formed so that the second compartment B isconnected to the fourth compartment D in the interior of the firstpiston 818. On the other hand, the third compartment C is arranged so asnot to be connected to the fourth compartment D. The fourth compartmentD is connected to the first flow passage 814. In other words, the fourthcompartment D is a space having a first opening 814 a, which is anopening of the first flow passage 814, at its inner side. Also, one ofeither of the second compartment B and the third compartment C isconfigured to become connected to the second flow passage 815 by slidingof the first piston 818. In other words, one of either of the secondcompartment B and the third compartment C is configured to have a secondopening 815 a, which is an opening of the second flow passage 815, inits interior by the sliding of the first piston 818.

Specifically, when the first piston 818 slides to a second end (fourthcompartment D) that is the side opposite to the first end (firstcompartment A) and the second compartment B becomes connected to thesecond flow passage 815, the second flow passage 815 is connected to thefirst flow passage 814 via the interior of the second compartment B1first piston 818 of the first cylinder portion 817 and the fourthcompartment D. This is the open state of the first valve 822. On theother hand, when the first piston 818 slides to the first end (firstcompartment A) and the third compartment C becomes connected to thesecond flow passage 815, the connection of the second flow passage 815and the first flow passage 814 is interrupted by the first piston 818.This is the closed state of the first valve 822.

A stopper member 819 is located at the second end of the first cylinderportion 817. A first spring 820, which is a compression spring, islocated between the stopper member 819 and the first piston 818. Thefirst spring 820 urges the first piston 818 toward the first end (firstcompartment A) by a comparatively small force. Therefore, when there isno difference between the gas pressure in the first compartment A, whichis the first end with reference to the first piston 818, and the gaspressure in the fourth compartment D, which is the second end, the firstpiston 818 is put in a state of being moved to the first end by theforce of the first spring 820. That is, the first valve 822 is put inthe closed state.

Yet further, one end of the second cylinder portion 823 is connected tothe volume chamber 811 and the other end is connected to the third flowpassage 816. Also, the second piston 824 is provided to be slidablealong the second cylinder portion 823 and is configured to partition aspace on the side corresponding to the volume chamber 811 and a space onthe side corresponding to the third flow passage 816 in the secondcylinder portion 823. Also, the second valve 825 and the third valve 826are formed by the second piston 824.

Among these, the second valve 825 is provided so as to be switchablebetween an open state in which the volume chamber 811 and the secondcylinder portion 823 are connected and a closed state in which theconnection of the volume chamber 811 and the second cylinder portion 823is interrupted.

On the other hand, the third valve 826 is provided so as to beswitchable between an open state in which the volume chamber 811 and thehole portion 828 are connected and a closed state in which theconnection of the volume chamber 811 and the hole portion 828 isinterrupted.

The opening/closing operation of the second valve 825 is linked with theopening/closing operation of the third valve 826. When the second valve825 is in the open state, the third valve 826 is in the closed state. Onthe other hand, when the second valve 825 is in the closed state, thethird valve 826 is in the open state.

Also, the second piston 824 is urged by the urging force of the secondspring 827 in the direction in which the second valve 825 is put in theclosed state and the third valve 826 is put in the open state.

Yet further, the space on the side corresponding to the volume chamber811, which is partitioned by the second piston 824 in the secondcylinder portion 823, and the second flow passage 815 are configured tobe connected.

Also, as mentioned above, the first flow passage 814 is configured toconnect the fourth compartment D of the first cylinder portion 817 tothe compressor 802 and the exhaust valve 803. As one example, theconnection to the compressor 802 and the exhaust valve 803 is made viathe drying portion 805. Also, as mentioned above, the second flowpassage 815 is configured to connect one of either of the secondcompartment B and the third compartment C of the first cylinder portion817 to the gas tank 807. It is further configured to connect the spaceon the side corresponding to the volume chamber 811, which ispartitioned by the second piston 824 in the second cylinder portion 823,to the gas tank 807 as well.

Also, the third flow passage 816 is configured to be connected to thefirst flow passage 814, which is connected to the drying portion 805.

Yet further, the hole portion 828 is connected to the throttle valve 812and the throttle valve 812 is configured to be capable of adjusting theflow rate of gas per unit time. Also, the throttle valve 812 isconnected to the atmosphere exhaust outlet 813, and the atmosphereexhaust outlet 813 is provided to be capable of discharging the gas tothe atmosphere.

The gas tank 807 has a first tank 807 a, a second tank 807 b, and athird tank 807 c. The first tank 807 a to the third tank 807 c areconnected in series and valves 807 d are respectively located betweenthe first tank 807 a and the second tank 807 b and between the secondtank 807 b and the third tank 807 c.

The operation of the valve device 810 in the air processing system 801will now be described in detail.

FIG. 21 is a cross-sectional view illustrating the operation of thevalve device 810 according to the present embodiment at the start of airinflow.

As mentioned above, when in the state where the exhaust valve 803 isclosed, compressed air is delivered from the compressor 802, thecompressed air is dried by the drying portion 805 and delivered to andstored in the gas tank 807 via the check valve 808.

In this process, the compressed air flows from the first flow passage814 into the fourth compartment D of the first cylinder portion 817 asshown in FIG. 21.

The compressed air also flows from the second flow passage 815 into thespace on the side corresponding to the volume chamber 811, which ispartitioned by the second piston 824 in the second cylinder portion 823.The gas pressure in the space on the side corresponding to the volumechamber 811, which is partitioned by the second piston 824 in the secondcylinder portion 823, is thereby made higher than the gas pressure inthe volume chamber 811.

Although the compressed air flows from the second flow passage 815 intothe third compartment C of the first cylinder portion 817, the firstvalve 822 is in the closed state. The compressed air that has flowedinto the third compartment C thus does not at all act on the firstpiston 818.

Further, the compressed air flows from the third flow passage 816 intothe space on the side corresponding to the third flow passage 816, whichis partitioned by the second piston 824 in the second cylinder portion823. The gas pressure in the space on the side corresponding to thethird flow passage 816, which is partitioned by the second piston 824 inthe second cylinder portion 823, is thereby made higher than the gaspressure in the volume chamber 811.

The gas pressure in the space on the side corresponding to the thirdflow passage 816, which is partitioned by the second piston 824 in thesecond cylinder portion 823 and the gas pressure in the space on theside corresponding to the volume chamber 811 move the second piston 824against the urging force of the second spring 827. The second valve 825is thus put in the open state and the third valve 826 is put in theclosed state.

Consequently, the compressed air flows at once from the second flowpassage 815 into the volume chamber 811 via the space on the sidecorresponding to the volume chamber 811, which is partitioned by thesecond piston 824 in the second cylinder portion 823. The gas pressurein the volume chamber 811 thus increases at once. At this point, thecompressed air flows from the volume chamber 811 into the firstcompartment A of the first cylinder portion 817. The gas pressure in thefirst compartment A of the first cylinder portion 817 and the gaspressure in the fourth compartment D are equal and the first piston 818thus does not move. That is, the first valve 822 stays in the closedstate.

FIG. 22 is a cross-sectional view illustrating the operation of thevalve device 810 of the present embodiment immediately after opening.

As mentioned above, when the gas pressure in the gas tank 807 reachesthe predetermined value, the pressure governor (non-illustrated) putsthe exhaust valve 803 in the open state.

Then as shown in FIG. 22, the gas pressure in the first flow passage 814decreases at once and the gas pressure in the fourth compartment Ddecreases at once with respect to the gas pressure in the firstcompartment A of the first cylinder portion 817. That is, the balance isdisrupted.

The first piston 818 thus slides towards the fourth compartment Dagainst the urging force of the first spring 820. The second compartmentB and the second flow passage 815 are thereby connected. That is, thefirst valve 822 is put in the open state. In this state, the second flowpassage 815 is connected to the gas tank 807 in a high pressure state.On the other hand, the first flow passage 814 is in a low pressure statein comparison to the second flow passage 815 because the exhaust valve803 is in the open state. The compressed gas stored in the gas tank 807thus flows from the second flow passage 815 into first flow passage 814via the second compartment B of the first cylinder portion 817, theinterior of the first piston 818, and the fourth compartment D. Further,the compressed gas flows into the drying portion 805, regenerates thedrying agent 806 of the drying portion 805, and is discharged via theexhaust valve 803 and the silencer 804.

In this process, the gas pressure in the third flow passage 816decreases at once as does the gas pressure in the first flow passage814. The gas pressure in the space on the side corresponding to thethird flow passage 816, which is partitioned by the second piston 824 inthe second cylinder portion 823, rapidly becomes lower than the gaspressure in the volume chamber 811.

The difference between the gas pressure in the space on the sidecorresponding to the third flow passage 816, which is partitioned by thesecond piston 824 in the second cylinder portion 823, and the gaspressure in the volume chamber 811, together with the urging force ofthe second spring 827, moves the second piston 824. The second valve 825is thus put in the closed state and the third valve 826 is put in theopen state.

Consequently, the compressed air begins to flow out from the volumechamber 811 to the hole portion 828 via the third valve 826. Thecompressed air that has flowed out is discharged from the atmosphereexhaust outlet 813 while being adjusted in flow rate by the throttlevalve 812. A residual pressure does not act on the discharge destinationand thus the compressed air continues to flow out until the gas pressurein the volume chamber 811 becomes equal to the atmospheric pressure.That is, no matter how many times the outflow is repeated, the amount ofcompressed air that flows out is stabilized.

Although the compressed air from the gas tank 807 acts to flow from thesecond flow passage 815 into the second cylinder portion 823, there isno possibility that it will move the second piston 824 in the directionof opening the second valve 825. This is because the first valve 822 isin the open state, the gas pressure in the first flow passage 814 issignificantly lower than the gas pressure in the second flow passage815, and the compressed air from the gas tank 807 actively flows fromthe second flow passage 815 to the first flow passage 814 via the firstcylinder portion 817.

FIG. 23 is a cross-sectional view illustrating the operation of thevalve device 810 of the present embodiment during operation of the airfeeding time adjusting function.

When, from the state shown in FIG. 22, the compressed air in the volumechamber 811 continues to be discharged from the atmosphere exhaustoutlet 813 via the third valve 826, the hole portion 828, and thethrottle valve 812 as shown in FIG. 23, the air pressure in the volumechamber 811 gradually decreases and becomes equal to the atmosphericpressure. The first compartment A of the first cylinder portion 817 isconnected to the volume chamber 811 as mentioned above. The gas pressurein the first compartment A also decreases until it becomes equal to theatmospheric pressure.

A state where the gas pressure in the first compartment A and the gaspressure in the fourth compartment D are balanced or a state where thegas pressure in the first compartment A is less than the gas pressure inthe fourth compartment D is then attained. The first piston 818 is thenmade to slide toward the first compartment A by the comparatively smallurging force of the first spring 820. That is, the first valve 822 isput in the closed state.

Consequently, the flow of the compressed air in the gas tank 807 fromthe second flow passage 815 to the first flow passage 814 via the firstcylinder portion 817 is interrupted.

As described above, the valve device 810 of the present embodiment isarranged with the air feeding time adjusting function so that when thepredetermined time (for example, 30 seconds) elapses from the point atwhich the exhaust valve 803 is put in the open state and the compressedair begins to flow out from the volume chamber 811 via the hole portion828, the dry compressed air in the gas tank 807 flows in reverse withrespect to the drying portion 805.

Also, the first piston 818, which switches the first valve 822 betweenthe open and closed states, is located in the first cylinder portion817, which is independent of the volume chamber 811. In regard to“independence,” a connection may be made so that the gas can flow fromone to the other of the first cylinder portion 817 and the volumechamber 811. It suffices to be a relationship where the first piston 818slides in the interior of the first cylinder portion 817 but does notslide in the interior of the volume chamber 811.

The first piston 818 can thus be increased in flexibility of shape.Specifically, there is no need to arrange a large diameter portion and asmall diameter portion that differ greatly in diameter, and the pistonmay be formed by portions of substantially uniform diameter.Consequently, the possibility of occurrence of axial deviation, in whichthe attitude of the first piston 818 becomes inclined with respect tothe movement direction, is reduced. The possibility of significantincrease of the sliding load due to axial deviation can also be reduced.

Also, the first spring 820 that urges the first piston 818 is configuredto slide the first piston 818 with a comparatively small force when thegas pressure in the first compartment A and gas pressure in the fourthcompartment D are balanced. Therefore, even upon repeated use, there isno possibility for the spring force of the first spring 820 to settleand become unable to move the first piston 818 properly.

Yet further, in comparison to another configuration described above (seeFIG. 28), the amount of inflow of compressed air per unit time into thevolume chamber 811 (reference numeral 843 in FIG. 28) can be madegreater by providing the second valve 825 and the third valve 826. Inother words, the compressed air of the predetermined amount can beaccumulated in the volume chamber 811 (reference numeral 843 in FIG. 28)in a short time.

With the other configuration described above (see FIG. 28),substantially the same length of time (for example, 30 seconds) as thetime (for example, 30 seconds) during which the air feeding timeadjusting function is activated to switch from the open state to theclosed state is required to accumulate the predetermined amount ofcompressed air. Although the time required for the drying agentregeneration differs variously according to system and is determined bythe opening diameter of the hole portion 842 (see FIG. 28) in the otherconfiguration, the time for filling the volume chamber with air (timeuntil the valve is opened) is also determined by the opening diameter ofthe hole portion 842 in the other configuration. The timing of thedrying agent regeneration is thus influenced by the air filling time andtherefore the requirement of rapid air filling and flexibility of timesetting of the air feeding time adjusting function for the regenerationprocess cannot be achieved at the same time. For example, if only 15seconds are available as the time for filling with air, sufficient airfilling cannot be performed for activating the air feeding timeadjusting function for 30 seconds and the air feeding time adjustingfunction is activated incompletely for just 15 seconds. The drying agentcannot be regenerated sufficiently in this case.

With the configuration of the present embodiment, the requirement ofrapid air filling and flexibility of time setting of the air feedingtime adjusting function for the regeneration process is achieved at thesame time.

Although in the embodiment described above, the hole portion 828 and thethrottle valve 812 are arranged separately, these may be configuredtogether.

Also, although the first valve 822 of the embodiment is a normallyclosed valve, which is normally in the closed state, attains the openstate just for a predetermined time (for example, 30 seconds) by apredetermined operation, and thereafter returns to the closed state, itmay be of an opposite configuration. Specifically, it may be of anormally open configuration, which is normally in the open state,attains the closed state just for a predetermined time (for example, 30seconds) by a predetermined operation, and thereafter returns to theopen state. This can be arranged, for example, by forming the firstpiston 818 in the embodiment so that the third compartment C and thefourth compartment D are in communication and the second compartment Band the fourth compartment D are not in communication.

A valve device (810) having the normally open configuration opens andcloses a bypass flow passage (814, 815) bypassing a flow passage of gasbetween a gas compressor (802) and a gas tank (807) storing the gassupplied from the gas compressor (802). The valve device (810) ischaracterized by a volume chamber (811) and a first valve (822). Theinternal pressure of the volume chamber (811) is increased in internalpressure by gas being supplied from at least one of either of the gascompressor (802) and the gas tank (807) and is decreased by the gasflowing out over a predetermined time (for example, 30 seconds) from ahole portion (828) in accompaniment with pressure reduction on the sidecorresponding to the gas compressor (802). The first valve (822) is incommunication with the volume chamber (811), closes the bypass flowpassage (814, 815) in accordance with pressure reduction on the sidecorresponding to the gas compressor (802) in a state where apredetermined pressure is reached at the volume chamber (811), andthereafter opens the bypass flow passage (814, 815) in accordance withreduction of the internal pressure of the volume chamber (811). Thefirst valve (822) is configured to open and close the bypass flowpassage (814, 815) by a piston (818) sliding inside a cylinder portion(817) formed independently of the volume chamber (811).

The valve device (810) is further characterized by the followingconfiguration. At least three ring-shaped sealing members (821) arearranged at appropriate intervals in the movement direction of thepiston (818) on the outer periphery of the piston (818) to partition theinterior of the cylinder portion (817) into at least four portions offirst to fourth spaces (first compartment A, second compartment B, thirdcompartment C, and fourth compartment D) in that order in the movementdirection of the piston (818). A first opening (814 a) in communicationwith the gas compressor side flow passage (814) in the bypass flowpassage (814, 815) and a second opening (815 a) in communication withthe gas tank side flow passage (815) in the bypass flow passage (814,815) are formed at a predetermined interval in the movement direction ofthe piston (818) in the inner wall of the cylinder portion (817). Thefirst space (A) is a space that is constantly in communication with thevolume chamber (811) regardless of the position of the piston (818). Thefourth space (D) is a space having the first opening (814 a) at itsinner side regardless of the position of the piston (818). The secondspace (B) is a closed space. The third space (C) is a space that isconstantly put in communication with the fourth space (D) by acommunication passage formed inside the piston (818). The piston (818)is urged in the direction of closing the first valve (822) by an urgingmeans (820). The first valve (822) is put in the open state by a statewhere the second opening (815 a) is positioned inside the third space(C) being maintained by balancing of the pressure acting on the piston(818) in the first space (A) and the pressure acting on the piston (818)in the fourth space (D) in the state where the gas is supplied from thegas compressor (802). The first valve (822) is put in the closed state,when, due to pressure reduction on the side corresponding to the gascompressor (802), the pressure acting on the piston (818) in the firstspace (A) overcomes the pressure acting on the piston (818) in thefourth space (D) to move the piston (818) until the second opening (15a) is positioned inside the second space (B). The first valve (822) isthereafter put in the open state when, due to reduction of the internalpressure of the volume chamber (811), the pressure acting on the piston(818) in the first space (A) decreases and the piston (818) is returnedby the urging force of the urging means (820) until the second opening(815 a) is positioned inside the third space (C).

Yet further, the compressed air flowing into the volume chamber 811 maybe supplied from the compressor 802 or may be supplied from the gas tank807. Also, the compressed air may also be supplied from both thecompressor 802 and the gas tank 807.

The valve device 810 of the present embodiment opens and closes thebypass flow passage (814, 815) bypassing the flow passage of gas betweenthe compressor 802 that is a gas compressor and the gas tank 807 storingthe gas supplied from the compressor 802. The valve device 810 ischaracterized by the volume chamber 811 and the first valve 822. Theinternal pressure of the volume chamber 811 is increased by gas beingsupplied from at least one of either of the compressor 802 and the gastank 807 and is decreased by the gas flowing out over a predeterminedtime (for example, 30 seconds) from the hole portion 828 inaccompaniment with pressure reduction on the side corresponding to thecompressor 802. The first valve 822 is in communication with the volumechamber 811, opens the bypass flow passage (814, 815) due to pressurereduction on the side corresponding to the compressor 802 in the statewhere the predetermined pressure is reached at the volume chamber 811,and thereafter closes the bypass flow passage (814, 815) due toreduction of the internal pressure of the volume chamber 811. The firstvalve 822 is configured to open and close the bypass flow passage (814,815) by the first piston 818 sliding inside the first cylinder portion817, which is a cylinder portion formed independently of the volumechamber 811.

The valve device (810) is further characterized by the followingconfiguration. The O-rings 821 are provided as at least threering-shaped sealing members at appropriate intervals in the movementdirection of the first piston 818 on the outer periphery of the firstpiston 818 to partition the interior of the first cylinder portion 817into the at least four portions of the first compartment A, the secondcompartment B, the third compartment C, and the fourth compartment D,which are the first to fourth spaces in that order in the movementdirection of the first piston 818. The first opening 814 a incommunication with the first flow passage 814, which is a flow passageon the side corresponding to the compressor 802 in the bypass flowpassage (814, 815), and the second opening 815 a in communication withthe second flow passage 815, which is a flow passage on the sidecorresponding to the gas tank 807 in the bypass flow passage (814, 815),are formed at the predetermined interval in the movement direction ofthe first piston 818 in the inner wall of the first cylinder portion817. The first compartment A, which is the first space, is constantly incommunication with the volume chamber 811 regardless of the position ofthe first piston 818. The fourth compartment D, which is the fourthspace, has the first opening 814 a at its inner side regardless of theposition of the first piston 818. The second compartment B, which is thesecond space, is constantly put in communication with the fourthcompartment D by the communication passage formed inside the firstpiston 818. The third compartment C, which is the third space, is aclosed space. The first piston 818 is urged in the direction of closingthe first valve 822 by the first spring 820, which is an urging means.The first valve 822 is put in the closed state by the state where thesecond opening 815 a is positioned inside the third compartment C beingmaintained by balancing of the pressure acting on the first piston 818in the first compartment A and the pressure acting on the first piston818 in the fourth compartment D in the state where the gas is suppliedfrom the compressor 802. The first valve 822 is put in the open state,when, due to pressure reduction on the side corresponding to thecompressor 802, the pressure acting on the first piston 818 in the firstcompartment A overcomes the pressure acting on the first piston 818 inthe fourth compartment D to move the first piston 818 until the secondopening 815 a is positioned inside the second compartment B. The firstvalve 822 is thereafter put in the closed state when, due to thereduction of the internal pressure of the volume chamber 811, thepressure acting on the first piston 818 in the first compartment Adecreases and the first piston 818 is returned by the urging force ofthe first spring 820 until the second opening 815 a is positioned insidethe third compartment C.

Yet further, the present embodiment is characterized by the second valve825 for filling the volume chamber 811 with the gas and the third valve826 for discharging the gas from the volume chamber 811 via the holeportion 828.

Also, the present embodiment is characterized in being configured suchthat the gas discharged from the volume chamber 811 via the hole portion828 is discharged to the atmosphere from the atmosphere exhaust outlet813.

The air dryer (805) of the present embodiment includes the dryingportion 805 having the regenerable drying agent 806 and the regenerationvalve device 810 connected to one end of the flow passage in the dryingportion 805. The air dryer (805) is characterized in that the dryingportion 805 is located between i) the compressor 802 and the exhaustvalve 803 and ii) the regeneration valve device 810, and the dryingagent 806 is dried using the gas in the gas tank 807 that flows inreverse when the exhaust valve 803 is opened and the first valve 822 isin the open state.

Also, the valve device 810 of the present embodiment is characterized bythe volume chamber 811, an intake inlet (formed by the third flowpassage 816) and an exhaust outlet (formed by the hole portion 828)provided in the volume chamber 811, and a valve (first valve 822) incommunication with the volume chamber 811. The first valve 822 opens orcloses for a predetermined time in accordance with a change of pressurein the volume chamber 811.

The present embodiment is also characterized by the followingconfiguration. In a compressed air supply system (air processing system801), the air dryer 805 is located in the supply flow passage betweenthe compressor 802 as a gas compressor and the gas tank 807 storing thegas supplied from the compressor 802. The check valve 808, which allowsthe flow of gas from the side corresponding to the air dryer 5 to theside corresponding to the gas tank 807, is located in the supply passagebetween the gas tank 807 and the air dryer 805. An intake inlet (formedby the third flow passage 816) and an exhaust outlet (formed by the holeportion 828) are provided in the volume chamber 811. A valve (the firstvalve 822) is provided that is in communication with the volume chamber811 and opens and closes in accordance with the pressure inside thevolume chamber 811. The first valve 822 is provided for opening andclosing a purge flow passage that puts a point between the gas tank 807and the check valve 808 and a point between the drying agent of the airdryer 805 and the check valve 808 in communication.

Additional Embodiment 1

Piping connections of a valve device 830 in the air processing system801 of an additional embodiment and the structure of the valve device830 will now be described.

FIG. 24 is a schematic cross-sectional view of the valve device 830according to the additional embodiment.

As shown in FIG. 24, the valve device 830 of the additional embodimenthas the volume chamber 811, a hole portion 831, the first cylinderportion 817, the first piston 818, the first flow passage 814, and thesecond flow passage 815.

For components that are the same as those of the embodiment describedabove, the same reference numerals will be used and description thereofwill be omitted.

There are several points in the valve device 830 of the additionalembodiment that differ from the above-described embodiment. Whereas withthe above-described embodiment (see FIG. 20 to FIG. 23), the third flowpassage 816 is used, this is not used in the additional embodiment.

In the above-described embodiment (see FIG. 20 to FIG. 23), the secondpiston 824 of the second cylinder portion 823 is moved to switch betweenopening and closing of the second valve 825 and the third valve 826. Incontrast, in the additional embodiment, the second piston 824 is notmoved. In the additional embodiment, the second valve 825 stays in theclosed state and the third valve 826 stays in the open state. That is,the second valve 825 and the third valve 826 are not used as valves thatopen and close. These are illustrated for reference to facilitate theunderstanding of other points of difference.

Yet further, in the above-described embodiment (see FIG. 20 to FIG. 23),the hole portion 828 is connected via the throttle valve 812 to theatmosphere exhaust outlet 813. In the additional embodiment, the holeportion 831 is connected via the throttle valve 812 to the first flowpassage 814.

The operation of the valve device 830 in the air processing system 801of the additional embodiment will now be described in detail.

FIG. 25 is a cross-sectional view illustrating an operation of the valvedevice 830 according to the additional embodiment at the start of airinflow.

As with the above-described embodiment, when the compressed air from thecompressor 802 is delivered in the state where the exhaust valve 803 isclosed, the compressed air is dried by the drying portion 805 and isdelivered to and stored at the gas tank 807 via the check valve 808.

In this process, the compressed air flows from the first flow passage814 into the fourth compartment D of the first cylinder portion 817 asshown in FIG. 25.

Although the compressed air also flows from the second flow passage 815into the third compartment C of the first cylinder portion 817, thefirst valve 822 is in the closed state. The compressed air that hasflowed into the third compartment C thus does not act at all on thefirst piston 818.

Yet further, the compressed air gradually flows into the volume chamber811 via the first flow passage 814, the throttle valve 812, and the holeportion 831. The gas pressure in the volume chamber 811 thus increasesgradually. The inflow is gradual because the amount of inflow per unittime is adjusted by the throttle valve 812.

In this state, the compressed air flows from the volume chamber 811 intothe first compartment A of the first cylinder portion 817. Therelationship between the gas pressure in the first compartment A of thefirst cylinder portion 817 and the gas pressure in the fourthcompartment D will now be described. In the process in which thecompressed air begins to flow from the hole portion 831 into the volumechamber 811, the gas pressure in the first compartment A is lower thanthe gas pressure in the fourth compartment D when the inflow beginsbecause the gas pressure in the volume chamber 811 increases gradually.Thereafter, the gas pressure in the volume chamber 811 increasesgradually and the gas pressure in the first compartment A becomes equalto the gas pressure in the fourth compartment D. From the beginning, thefirst piston 818 is positioned on the side corresponding to the firstcompartment A by the urging force of the first spring 820. Thereforeuntil the gas pressure in the first compartment A increases graduallyand becomes equal to the gas pressure in the fourth compartment D, thefirst piston 818 does not move. That is, the first valve 822 stays inthe closed state.

FIG. 26 is a cross-sectional view illustrating the operation of thevalve device 830 according to the additional embodiment immediatelyafter opening.

As with the embodiment described above, when the gas pressure in the gastank 807 reaches the set predetermined value, the pressure governor(non-illustrated) puts the exhaust valve 803 in the open state. The gaspressure in the first flow passage 814 thus decreases at once. The gaspressure in the fourth compartment D then decreases at once.

On the other hand, although the compressed air in the volume chamber 811begins to flow out via the hole portion 831, the amount of outflow perunit time is restricted because the outflow occurs via the throttlevalve 812. The gas pressure in the volume chamber 811 thus decreasesgradually.

Therefore, immediately after the exhaust valve 803 is put in the openstate, the gas pressure in the fourth compartment D decreases at oncewith respect to the gas pressure in the first compartment A of the firstcylinder portion 817. That is, the balance is disrupted.

Therefore as shown in FIG. 26, the first piston 818 slides to the fourthcompartment D side against the urging force of the first spring 820. Thesecond compartment B and the second flow passage 815 are therebyconnected. That is, the first valve 822 is put in the open state.

Consequently, as in the above-described embodiment, the compressed gasstored in the gas tank 807 flows from the second flow passage 815 intofirst flow passage 814 via the second compartment B of the firstcylinder portion 817, the interior of the first piston 818, and thefourth compartment D. Further, the compressed gas flows into the dryingportion 805, regenerates the drying agent 806 of the drying portion 805,and is discharged via the exhaust valve 803 and the silencer 804.

Although the compressed air from the gas tank 807 acts to flow from thesecond flow passage 815 into the second cylinder portion 823, there isno possibility that it will move the second piston 824 in the directionof opening the second valve 825. This is because the first valve 822 isin the open state, the gas pressure in the first flow passage 814 issignificantly lower than the gas pressure in the second flow passage815, and the compressed air from the gas tank 807 actively flows fromthe second flow passage 815 to the first flow passage 814 via the firstcylinder portion 817. Another reason is that the urging force of thesecond spring 827 is acting. Yet another reason is that the gas pressurein the volume chamber 811 is high.

FIG. 27 is a cross-sectional view illustrating the operation of thevalve device 830 according to the additional embodiment during operationof the air feeding time adjusting function.

When, from the state shown in FIG. 26, the compressed air in the volumechamber 811 continues to be discharged from the exhaust valve 803 viathe hole portion 831 and the throttle valve 812 as shown in FIG. 27, theair pressure in the volume chamber 811 gradually decreases. The airpressure then becomes equal to the atmospheric pressure.

Therefore, as in the above-described embodiment, the gas pressure in thefirst compartment A and the gas pressure in the fourth compartment D arebalanced. The first piston 818 is then made to slide toward the firstcompartment A by the comparatively small urging force of the firstspring 820. That is, the first valve 822 is put in the closed state.

Consequently, the flow of the compressed air in the gas tank 807 fromthe second flow passage 815 to the first flow passage 814 via the firstcylinder portion 817 is interrupted.

As described above, the valve device 830 of the additional embodimenthas the air feeding time adjusting function. That is, when thepredetermined time (for example, 30 seconds) elapses from the point atwhich the exhaust valve 803 is put in the open state and the compressedair begins to flow out from the volume chamber 811 via the hole portion831, the dry compressed air in the gas tank 807 flows in reverse withrespect to the drying portion 805.

Also, the first piston 818, which switches the first valve 822 betweenthe open and closed states, is located in the first cylinder portion817, which is independent of the volume chamber 811. The first piston818 can thus be increased in the flexibility of shape and in regard tothis point, the same actions and effects as the above-describedembodiment are obtained.

Also, the first spring 820, which urges the first piston 818, isconfigured to slide the first piston 818 with a comparatively smallforce when the gas pressure in the first compartment A and gas pressurein the fourth compartment D are balanced. The same actions and effectsas the above-described embodiment can thus be obtained.

With the additional embodiment, although the second cylinder portion823, the second piston 824, the second valve 825, and the third valve826 used in the above-described embodiment are illustrated, these arenot used. In regard to the technical idea of reducing the axialdeviation, and the like, the third flow passage 816, the second cylinderportion 823, the second piston 824, the second valve 825, and the thirdvalve 826 do not have to be provided.

Additional Embodiment 2

A valve device 850 according to another additional embodiment will nowbe described with reference to FIGS. 28 and 29. FIGS. 28 and 29 arecross-sectional views of an air dryer 805′ in which the valve device 850according to the additional embodiment is installed. With the air dryer805′ and the valve device 850 shown in FIGS. 28 and 29, the sameconfigurations as those of the already-described embodiment are providedwith the same reference numerals and description thereof will be omittedbelow.

Unlike the above-described embodiment, with the valve device 850 shownin FIGS. 28 and 29, the stopper member 819 is eliminated and the O-ringprovided in the stopper member and fixing ring for mounting the stoppermember 819 are also eliminated to achieve reduction of the number ofparts and reduction of cost.

To be more specific, reference numeral 51 in FIGS. 28 and 29 denotes abase member that forms a base of the valve device 850 (base of the airdryer 5′), and the volume chamber 811 and the first cylinder portion 817are formed in the base member 851.

The first piston 818 is housed in the first cylinder portion 817 and alid member 852 is mounted and fixed thereabove on the opening of thefirst cylinder portion 817 by a non-illustrated fixing means. An openingportion 852 a formed in the lid member 852 puts the first cylinderportion 817 and the volume chamber 811 in communication. The volumechamber 811 is closed by a lid member 853, which is mounted and fixed onthe base member 851 by a non-illustrated screw.

With the valve device 850 with the above configuration, when thecompressed air is delivered from the compressor 802, the gas tank 807 isfilled with the dry-compressed air that has been dry-processed by thedrying agent 806 and the volume chamber 811 is filled with thecompressed air (arrows in FIG. 28) in the same manner as in the valvedevice 810 described above.

In this state, the first valve 822 is closed.

Thereafter, when the pressure inside the gas tank 807 reaches apredetermined value and the exhaust valve 803 opens, the first valve 822opens and the compressed air inside the volume chamber 811 flows to thedrying agent 806 via the throttle valve 812 for a predetermined time(arrows in FIG. 29). The first valve 822 is open during this state andthe dry air in the gas tank 807 thus flows toward the exhaust valve 803via the drying agent 806 during this state. The drying process of thedrying agent 806 is thereby performed. The operation of the entiretyincluding the valve device 850 is thus the same as that of thealready-described embodiment.

The valve device 850 in the present embodiment is configured such thatthe base member 851 (bottom portion 851 a of the first cylinder portion817) itself is used in place of the stopper member 819 in the embodimentshown in FIG. 20 and therefore the stopper member 819 and the fixingring, and the like, for mounting the stopper member 819 is eliminated toachieve reduction of the number of parts and reduction of cost.

The present invention is not restricted to the above-describedembodiments, various modifications are possible within the scope of theinvention described in the claims, and obviously such modifications areincluded within the scope of the present invention.

With the present invention, a better silencing effect is obtained in thesilencer provided in the air dryer for performing the drying process oncompressed air. Yet further, for the second object of obtaining asilencer that does not require a large occupied volume, the silencer230, which reduces the air discharge noise from the exhaust valve 209that discharges the drain generated by the drying process in the airdryer 201 for performing the drying process on compressed air, includesthe expansion chamber 232, which has the plurality of inner walls 233Ato 233C respectively facing the plurality of slits 225A to 225C, whichare drain and air discharging outlets, and the noise absorbing materialhousing chamber 236, which is connected to the expansion chamber 232 andhouses the noise absorbing material 237. The air discharged from theplurality of slits 225A to 225C respectively hits the plurality of innerwalls 233A to 233C and thereafter passes through the noise absorbingmaterial 237 and are discharged from the micropores 241.

For the third object of achieving simplification of structure and lowcost in an exhaust valve provided in an air dryer that performs a dryingprocess on compressed air supplied from an air compressor, the exhaustvalve 305 has the valve, in which the piston 307 and the valve element309 are formed integrally. The valve is provided to be pressed in thevalve opening direction by the pressure of the compressed air suppliedfrom the air compressor. The exhaust valve 305 includes the returnspring 311 as the urging means that urges the valve in the valve closingdirection against the pressure of the compressed air supplied from theair compressor. When the air compressor is in the load state, the valveclosed state is maintained by the urging force of the return spring 311and the valve is opened by receiving the control command pressure fromthe pressure governor.

For the fourth object of providing a regeneration valve device for anair dryer that takes into consideration the simultaneous achievement ofthe requirement of rapid air filling and flexibility of time setting ofthe air feeding time adjusting function for the drying agentregeneration process, the regeneration valve device 510 for an air dryerincludes the piston 514, the valve (528, 531), the urging means 526, thehole portion (516), and the auxiliary passage (533). The piston 514defines in the interior of the chamber 511 the first end space on theside corresponding to the gas tank and the second end space on the sidecorresponding to the drying portion. The valve (528, 531) is closed bythe movement of the piston toward the first end and is opened by themovement of the piston toward the second end. The urging means 526 urgesthe piston in the direction of closing the valve. The hole portion (516)is formed in the piston and makes the gas flow from one side to anotherside in accordance with the difference between the pressure of the gasinside the first end space and the pressure of the gas inside the secondend space. The auxiliary flow passage (533) has the restricting means(521, 529). The restricting means (521, 529) allows the flow of gas inthe direction from the second end space to the first end space andrestricts the flow of gas in the direction from the first end space tothe second end space.

To achieve the fifth object of providing a compressed air supply devicefor a vehicle with a simplified configuration, the compressed air supplysystem 601 is provided, which includes the compressor 604 installed inthe vehicle and the air dryer 632. The air dryer 632 removes moistureand other foreign matter contained in the compressed air discharged fromthe compressor 604. The compressed air supply system 601 supplies thecompressed air passed through the air dryer 632 to the brake device ofthe vehicle. The system 601 further includes the regeneration means forregenerating the drying agent of the air dryer 632 at the predeterminedtiming and the vehicle speed detector 606 for detecting the vehiclespeed of the vehicle. The ECU 602 inhibits the regeneration of thedrying agent regardless of the predetermined timing if the detectedvehicle speed is slower than the reference speed.

For the sixth object of providing a valve device that takes intoconsideration the sliding of a piston for performing opening and closingof a valve having an air feeding time adjusting function, the valvedevice 810 is provided that includes the volume chamber 811 and thefirst valve 822. The internal pressure of the volume chamber 811 isincreased by gas being supplied from at least one of either of the gascompressor (802) and the gas tank 7 and is decreased by the gas flowingout over the predetermined time from the hole portion 828 inaccompaniment with pressure reduction on the side corresponding to atthe gas compressor The first valve 822 is in communication with thevolume chamber, opens the bypass flow passage (814, 815) due to pressurereduction on the side corresponding to the gas compressor in the statewhere the predetermined pressure is reached at the volume chamber, andthereafter closes the bypass flow passage (814, 815) due to reduction ofthe internal pressure of the volume chamber. The first valve 822 isconfigured to open and close the bypass flow passage (814, 815) by thepiston (818) sliding inside the cylinder portion (817) formedindependently of the volume chamber 11.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1 Air circuit-   5 Protection valve-   6˜9 Air tank-   10, 201, 632 Air dryer-   58, 506, 806 Drying agent-   211, 308, 520, 546, 821 O-ring-   604, 802 Compressor (air compressor)-   209, 305, 803 Exhaust valve-   231 Silencer case portion-   232, 320 Expansion chamber-   303 Control chamber-   304 Pressure chamber-   321 Noise absorbing material housing chamber-   504 Silencer-   601 Compressed air supply system (compressed air supply device for a    vehicle)-   602 ECU (regeneration control means, regeneration inhibiting means,    forcible regeneration means)-   605 Engine-   606 Vehicle speed detector (vehicle speed detecting means)-   608 Switch-   610 Air dryer module-   721˜723 Pressure sensor

1. A valve device configured to open and close a bypass flow passagebypassing a flow passage of gas between a gas compressor and a gas tankstoring the gas supplied from the gas compressor, comprising: a volumechamber wherein the internal pressure of the volume chamber is increasedby gas being supplied from at least one of the gas compressor and thegas tank and is decreased by gas flowing out over a predetermined timefrom a hole portion in accompaniment with pressure reduction on the sidecorresponding to the gas compressor; and a first valve in communicationwith the volume chamber, wherein the first valve is configured to openthe bypass flow passage due to pressure reduction on the sidecorresponding to the gas compressor in a state where a predeterminedpressure is reached at the volume chamber, and thereafter close thebypass flow passage due to reduction of the internal pressure of thevolume chamber, wherein the first valve is configured to open and closethe bypass flow passage by a piston sliding inside a cylinder portionformed independently of the volume chamber.
 2. The valve deviceaccording to claim 1, wherein at least three ring-shaped sealing membersare arranged at appropriate intervals along the movement direction ofthe piston on the outer periphery of the piston to partition theinterior of the cylinder portion into at least four portions of first tofourth spaces in that order in the movement direction of the piston, afirst opening in communication with the gas compressor side flow passagein the bypass flow passage and a second opening in communication withthe gas tank side flow passage in the bypass flow passage are formed ata predetermined interval in the movement direction of the piston in theinner wall of the cylinder portion, the first space is a space that isconstantly in communication with the volume chamber regardless of theposition of the piston, the fourth space is a space having the firstopening at its inner side regardless of the position of the piston, thesecond space is a space that is constantly put in communication with thefourth space by a communication passage formed inside the piston, thethird space is a closed space, the piston is urged in the direction ofclosing the first valve by an urging member, the first valve is put inthe closed state by a state where the second opening is positionedinside the third space being maintained by balancing of the pressureacting on the piston in the first space and the pressure acting on thepiston in the fourth space in the state where the gas is supplied fromthe gas compressor, the first valve is put in the open state when, dueto pressure reduction on the side corresponding to the gas compressor,the pressure acting on the piston in the first space overcomes thepressure acting on the piston in the fourth space to move the pistonuntil the second opening is positioned inside the second space, thefirst valve is thereafter put in the closed state when, due to reductionof the internal pressure of the volume chamber, the pressure acting onthe piston in the first space decreases and the piston is returned bythe urging force of the urging member until the second opening ispositioned inside the third space.
 3. The valve device according toclaim 1, further comprising a second valve for filling gas into thevolume chamber and a third valve for discharging the gas from the volumechamber via the hole portion.
 4. The valve device according to claim 3,wherein the gas discharged from the volume chamber via the hole portionis released to the atmosphere.
 5. An air dryer, comprising: a dryingportion having a regenerable drying agent; and a regeneration valvedevice connected to a first end of a flow passage in the drying portion,wherein the regeneration valve device is the valve device according toclaim 1, the drying portion is located between the regeneration valvedevice and both the gas compressor and the gas discharge valve, and thedrying agent is dried using the gas in the gas tank that flows inreverse when the gas discharge valve is opened and the first valve opensthe bypass flow passage.
 6. A regeneration valve device for an airdryer, comprising: a chamber that is located between a drying portionthat performs a drying process on a compressed gas supplied from a gascompressor and a gas tank that stores the dry compressed gas that hasundergone the drying process, wherein the pressure of the gas acts onthe chamber; a piston configured to move inside the chamber and definethe interior of the chamber into a first end space on the sidecorresponding to the gas tank and a second end space on the sidecorresponding to the drying portion; a valve configured to be put in aclosed state by the piston moving toward the first end and to be put inan open state by the piston moving toward the second end; an urgingmember that urges the piston in the direction in which the valve isclosed; a hole portion that is formed in the piston and makes the gasflow from one side to another side in accordance with the differencebetween the pressure of the gas inside the first end space and thepressure of the gas inside the second end space, and; an auxiliary flowpassage having a restricting member that allows the flow of gas in thedirection from the second end space to the first end space of thechamber and restricts the flow of gas in the direction from the firstend space to the second end space in the flow passage.
 7. Theregeneration valve device according to claim 6, wherein the auxiliaryflow passage is formed by a clearance between the outer peripheralsurface of a flange portion of the piston and the inner peripheralsurface of the chamber, the restricting member is formed by a cup sealhoused in a recessed portion formed along the outer peripheral surfaceof the flange portion such that an opening portion faces the first endspace; the cup seal enlarges and reduces the opening portion by elasticdeformation; the gas flows into the first end space via the hole portionand additionally via the auxiliary flow passage due to the openingportion of the cup seal reducing to open the clearance when the gasflows from the second end space in the chamber into the first end space,and the gas flows out to the second end space only via the hole portiondue to the opening portion of the cup seal enlarging to close theclearance when the gas flows out from the first end space in the chamberto the second end space.
 8. The regeneration valve device according toclaim 6, wherein the gas is delivered from the drying portion to thesecond end space in the chamber, the gas delivered into the second endspace flows into the first end space in the chamber, the pressure in thefirst end space in the chamber increases so that the piston is moved bythe pressure to the second end against the urging force of the urgingmember and the valve is put in the open state by the movement of thepiston, and by the gas in the first end space in the chamber flowing outto the second end space via the hole portion and the pressure in thefirst end space in the chamber decreasing due to the outflow of the gas,the urging force of the urging member moves the piston to the first endand the valve is put in the closed state by the movement of the piston.9. An air dryer comprising: a drying portion having a regenerable dryingagent; and a regeneration valve device connected to a first end of aflow passage in the drying portion, wherein the regeneration valvedevice is the regeneration valve device according to claim 6, and a gascompressor and a gas discharge portion are connected to the second endof the flow passage in the drying portion, and the valve of theregeneration valve device is put in the open state by the gas beingdelivered by the gas compressor to the first end space inside chambervia the hole portion and the auxiliary flow passage of the regenerationvalve device, and by the gas discharge portion being put in anatmosphere released state, the dry compressed gas inside the gas tank isdelivered to the drying portion via the valve of the regeneration valvedevice and discharged from the gas discharging portion.